I think the perceived quiet is a combination of Creative's domination and tendency towards stagnation. By this latter, I mean sticking with the same hardware for so long, and when finally providing a jump into new hardware technologies, doing so out of sync with the rest of the industry's "new shiny things" (i.e., not getting behind PCI-e, a combination of Vista's short circuit of EAX and migration issues in driver support for it, that type of thing). This is a big contrast to the CPUs and GPUs, for example.
There is news, though:
There are some recent C-Media Oxygen based sound cards that have become available (there are several, do a search for "Oxygen HD sound" or something).
There is also something coming from Asus, the Xonar D2 & D2X, which seem targeted at filling in exactly where Creative falls short: The D2X is PCI-e, and there seem to be rumblings of some sort of special efforts towards drivers, which would seem to indicate Vista as a priority. What is unclear to me at this point is whether it is "just another" Oxygen HD effort (high quality sound capabilities and making some advances in home theater functionality), or if it also has some more advanced signals processing hardware so it will actually compete with X-Fi on all fronts. One mention, on the level of rumor still AFAICS, seems to indicate 3D position hardware sound processing, so things might liven up soon.
