Mendeley comes out of stealth with its "Last.fm for academic research"
uk.techcrunch.com
uk.techcrunch.com
I think the analogy is that their software will show what papers you have on your computer, which would indicate that you have read them and might reference them.
However, in general, the idea of doing passive (meaning, implicitly gathered) collaborative filtering / recommendations on research is something that I find interesting, being a recommender systems mensch and all. This is one of the problems I'd like to see solved as a way of pulling in research that's in my field that I'm not yet familiar with, so I hope it works out for them.
Also, I want them to integrate with the university library system like google does so that I can get authenticated access to the documents.
Of course, I'm not great with naming domains myself, so maybe I'm the only one who would think that.