I think the most active people here got their heads in the beta right now, trying to be one step ahead so that some addons will work when the expansion hits
It's not a tiny piece of work.
And yeah, while cataclysm has been going on blizzard have lost a big number of subscribers, and the community too for sure, even if it's not as many.
And I'd like to say the community is rolling on good, it's been competitions and forum posts and updated/new compilations like always, there's just not as many posts in the 'here's my UI'-threads
Which got their own part of the forums now btw!