There's a distinction to be made between self-referential stories and metafictional stories. While self-reference rolls itself up into a ball, seeking to disappear in indexicality, metafiction sprawls, unfolds, and interrogates the consequences of self-reference and parody more than it engages in either. In metafiction is room for development, where self-reference aims for merely a more pithy postmodern version of the modernist paradox Frederic Jameson describes so well: resolution in paradox, fragmentation that effectively means closure--all of which announces the inflexibility of form at the same time as it mourns the loss of an unironic formal achievement. Of course, modernism can't be reduced to just that, but this is precisely the reduction postmodernism accomplishes in order to turn this fatalism into a weird schizophrenic joy, closing off all the utopian modernist alternatives in order to elaborate, rather than change, this relation to form. So the pithiness here comes from the sense that metafiction can be dissolved into a series of instances of self-reference (otherwise known as allegory), or the sense that in instances of self-reference, we are getting all that metafiction allows.
But the overturning of this relation between the two has itself to be overturned, set back on it's feet. Instead of narratives like that of "Seinfeld," which rigorously--and wonderfully, in its last episode, though everyone hated precisely this fact--stuck to its self-referential pseudo-closure, we need more stories like "It's Garry Shandling's Show," which is a wonderful example of the possibilities of meta-fiction. Where "Seinfeld" constantly got laughs because it was a parody of the sitcom's premise, a show about shows and so really "about nothing"--or, to put it more accurately, referring (via its plots mostly) constantly to its own status as merely plausible--"It's Garry Shandling's Show" allows Shandling the metafictional possibility of actually commenting upon the way the show will unfold, and motivating this moment of self-reference into a drama: plots often involve Garry trying to avoid having to do an upcoming scene, and all self-reference actually dissolves into a fiction that is actually about fiction. Rather than making fiction's status as merely probable the beginning and end of the story, the status actually motivates a story about fiction.
The difference is subtle (I have a little difficulty bringing it out here), but the effect is a completely different sort of tale: while "Seinfeld" maintains the division between fiction and reality and exploits it, "It's Garry Shandling's Show" has no use for such self-consciousness of fictionality, and spills over into reality, blurring it's lines. This produces, basically, realism's brand of fiction (it's this more than anything like the science fiction of which Latour speaks). Garry maintains the notion that you can actually come over to his show, and often invites the audience in for dip: the point is not that the show is accounting for it's status as a show, but rather that you don't know where the fiction begins or ends. Garry is a guy who can be on a stage and be fictional--fiction is something different than acting, in other words, or it is only that. The odd doubling-over that Latour describes so well as the point of a dualistic notion of reference--this is just another event in reality, and can interact with it only because reality is really not as opposed to fiction as we thought it was.
Another way of making the distinction is to say that the opposition of fiction is not reality but history, not in the sense that fictions are ahistorical (though this actually does apply in some ways), but that fictions are negated by an idea of reality that claims to be objective and different than the narratives we tell about it. Fiction has no problem dealing with reality, but when it meets the claim that the people it deals with are not historical persons (and, as Michael Wood explains, especially when they are real people who are embellished through fiction, like the heroes of Homer Aristotle has so many problems with), it then has all sorts of problems. It's only when we believe reality has anything to do with history in this sense that reality then becomes opposed to fiction in such an austere way. Otherwise, like Latour says, the world interprets itself: what's crucial is that meta-fiction tries to restore this state of things, while self-reference or the restricted play between allegory and irony, comes from that despairing state of things just described, and will preserve the distinction between historical reality and fiction at all costs.
A final note: I had a little trouble distinguishing between the self-referential and the metafictional above, partly because "Seinfeld" is only explicitly self-referential in its form, and this actually makes it less visible (thus the disappointment with the last episode came from people mistaking the show's form for something else that involved the sort of everyday comedy that was its subject, something that would be about something). A cleaner example might be a reality show, especially one about trying to get on TV: Kathy Griffin's reality show is a good one, while "The Comeback" is pretty much a perfect example, because it takes the premise of reality TV (something lurking behind both Shandling and Seinfeld's ventures, but not really crystallized yet) to the max, and shows it to be precisely this sort of infinite self-reference. But that's still too formal, even if it shows just how dead and boring postmodernism is when it's view of things really hits TV. A more direct example can just be taken from "It's Garry Shandling's Show," since it uses self-reference to get to the plane of metafiction. The direct reference in the scene above to the monologue that opens the show is self-referential, while what it implies in terms of action is metafictional: Nancy has to stop what she's doing to wait for Garry to finish the monologue, because it's a monologue, something that, in fiction, has a particular shape and has to be traversed in a particular fashion--and not just because Garry refers to the show and what he is doing in general, in the abstract. What's funny is the waiting, and then the fact that she realizes that because the monologue is this particular object (I think like the realists we might call it an "object," or at least that's my take on how to turn people like Harman towards narrative, via their excellent reflections on what is involved in aesthetics) she can go do something else while Garry finishes--it's this that's funny, not the reference. You can also probably distinguish between them if you look at the great theme song, though things get hazy when you try to distinguish between types of utterance, as Derrida a long time ago (and this realist possibility of metafiction is, in my reading of him, what he tries to preserve here) showed with Austin:
This is the theme to Garry's show,
The theme to Garry's show,
Garry called me up and asked if I would right his theme song,
I'm almost halfway finished,
How do you like it so far,
How do you like the theme to Garry's show.
This is the theme to Garry's show,
The opening theme to Garry's show,
This is the music that you hear as you watch the credits,
We're almost to the part of where I start to whistle,
Then we'll watch "It's Garry Shandling's Show."
This was the theme to Garry Shandling's show.
"This is the theme to Garry's Show" is self-reference, while the amazing, hilarious turn "I'm almost halfway finished," picks up the narrative potential in "Garry called me up" and starts something metafictional, which doesn't take the plausibility of fiction for granted, and doesn't try to shore it up, but explores it, makes it spill out into and merge with reality.