Season seven was heavily rumoured to be the last season of the show, but then I think the writer's strike interfered with it, or something, and they've decided they need another one to wind it down.
ABC has apparently been interested in Scrubs for a while (which is my sentimental favourite comedy of all-time, and in my opinion, the best show on television today), so they might treat it better than NBC did. The show continues to find more and more success on DVD, so I'm hoping that it gets the glory it deserves eventually (a Best Comedy Emmy and some awards for the cast).
I'm so glad they're doing an eighth season.