I don't know about you but I'm seriously waiting for Icecrown Citadel. Not that I've finished
all the content, I've yet to see Yog Sarron die, but that requires several evenings on Udluar and most people don't spend that amount of time on this raid anymore. Too much "free loot" on ToC (normal) or Onyxia or Lolaron to motivate much people about Ulduar.
I still think Ulduar is the best raid from WotLK up to now, despite it being too big, it should have been split in two raids as it was done all along BC. I still have some friends motivated by Ulduar hard modes and we're trying them from time to time, usually one or two nights a week when we are lucky enough to make our suicidal squad (Auriaya with all cats is a crazy fun mess of a fight to heal). If I find ToC hard mode mostly a "gear check", Ulduar hard modes are, at least for some of them, very entertaining.
The first news from the next raid Blizzard is giving us are starting to appear, and the first boss was tested on the PTR these last days (report on Mmo Champion). It doesn't seem super hard, as least on paper, I hope the normal/hard mode gap will be lower then ToC, and my wish is for hard modes to contain more abilities, more strategy than just be a gear check put over a normal difficulty boss.
I guess we'll all see that in IC, hopefully not too long from now, but even more hopefully nicely tested and balanced.