Clive Barnett of Pop Theory writes an interesting and lengthy musing on Latour's AIME (helpfully linked to by the ever helpful ANTHEM blog). He draws a number of very useful links between Latour's use of speech act and other elements of linguistic philosophy.
I think he may be right about Latour overstating the language-reductiveness of speech act theory, etc. and analytic philosophers certainly are interested in being as well as language. However, I think it's also fair to say that Latour goes a long way beyond where any of these people end up.
In AIME he argues the following (I paraphrase loosely but, I think, accurately) with regard to language and metaphysics: everything relates with or 'passes through' something else in order to continue existing; therefore everything joins things together, everything 'articulates'; each mode is a particular kind of articulation, a particular way of relating; thus every mode can be understood as having different truth procedures or standards of meaning; everything articulates, everything interprets, everything judges—from tics to popes, as Latour puts it at one point; language is just one way of articulating, among others, though it is not a mode itself but a mixture, presumably, of [tec]hnology, [fic]tion and others; when we speak or write we are simply taking advantage of a capacity that already exists in the world—namely, articulation; language is an invention that utilises and renders unusually explicit and dynamic what was there all along; thus we can understand the world in language, not as a 'lens' or anything of the sort but as something with real purchase on how things are because meaningful articulation is how things are.
Making AIME all about language is, therefore, rather misleading. Although it makes use of lots of linguistic philosophy it's utterly metaphysical at heart. To suggest that 'ontology' and 'metaphysics' are empty signifiers because it's really all about language—that misses the whole point of what Latour is trying to do. Saying that 'practices' also have a meaningful structure and therefore discourse theory, etc. isn't all about language isn't sufficient either—that's like an agoraphobic setting one foot outside his front door and saying that he's been around the world and back.
For Latour the evolution of sea algae in and of itself is as meaningful and articulated as this sentence, as any sentence. I can't see Searle et al. getting on board with that! Now, that's not to say that there can't be all sorts of productive conversations between these thinkers of language and meaning but, suffice to say, I don't think that ontology and metaphysics are empty signifiers.