There seems to be two main "movements" in science fiction (and I'm talking about science fiction, not the broader speculative fiction/fantasy etc.) at this point in time. Both were mentioned in the editorial in the October '07 issue of Asimov's. The first is the manifesto-wielding vanguard of Mundane SF that I've mentioned in an earlier post. The second movement has been called "New Space Opera," which has no manifesto I know of, or a website for that matter.
The name "New Space Opera" seems to have come into currency with a 2003 edition of Locus (a role that an upcoming issue of Interzone seems to be planning to play for Mundane SF) and has not had a terribly clear definition, but my favorite one is by Paul McAuley from that same Locus issue.
There are neither empires nor rigid technocracies dominated by a single Big Idea in the new space opera; like cyberpunk, it's eclectic and pluralistic, and infused with the very twenty-first century sensibility that the center cannot hold, that technology-driven change is continuous and advancing on a thousand fronts, that some kind of posthuman singularity is approaching fast or may already have happened. Most of all, its stories contain a vertiginous sense of deep time; in the new space opera, the Galaxy is not an empty stage on which humans freely strut their stuff, but is instead a kind of junk yard littered with the ruins and abandoned wonders of earlier, more powerful races.
The mention of the singularity is key IMO, as it seems one of the main differences in content between the "Old" and the "New" Space Opera is the whole concept of a "singularity." New Space Opera takes the singularity as a given and either goes with it, or establishes some explanation of why AI/Nanotech/Etc. isn't completely warping the setting beyond explanation.
I mention all this because the Apotheosis Trilogy I'm working on may, by the third volume, fit into this description-- closest I've ever been to being part of a literary movement.