First heard about facebook from a Egyptian colleague (Shrief) for viewing the photos of the trip with him and others.
After joining facebook, I found many Red Hatters there, and after that I also met many ex-colleagues. Today I asked several U-mates about facebook, and some of them have accounts!
Meeting new friends is amazing, but more amazing thing is meeting old friends which haven't meet frequently or even "disappeared" for a long time.
Facebook is such kind of thing, yes, really amazing.
http://facebook.com/