We have a room there for life scientists that's ended up being one of the best sources of info out there. None of us have ever found any use for Digg (and to a lesser extent Reddit). The best part, people really not into Twitter, etc have joined up. It's like a hybrid between a newsgroup and IRC but with a slicker, easier interface.
And yes, Twitter is a totally different beast and that's a good thing
Most of the times I stumble on good site/article and really really nice pictures from flickr
and yes its unlike twitter. Twitter is like IM and you are allowed to communicate through status message. Its hip but how useful?