Good link, thanks Sonja! As you say, it depends on how many people sign up. I've posted the link to the facebook group I created yesterday for English Lit postgrads, hopefully can get some of them to join.
In a sense academia.edu is like Facebook for academics, but a more explicit tool could be so much more valuable. One thing I find disappointing is that you can't search someone's 'About Me' section, as far as I can tell. My research is on a very specific topic (McSweeney's) and so it would be incredibly useful to search for other people working on that. Perhaps it's a feature that will emerge, or perhaps once listings filter through to Google indexing it will be possible to search that way, as the 'Keywords' feature would seem to suggest.
I fear that not many Goldsmiths researchers will join, but who knows!