http://www.thelocal.se/6219/. This article says Second Life is approaching 3 million users, a third of them having joined in the last 60 days. A lot of companies are jumping on the Second Life bandwagon, but this is even more interesting.
I met the founder of Linden Lab, the maker of Second Life, at the 2005 AlwaysOn conference at Stanford University. His vision is now paying off, not only for his company, which recently attracted its 1 millionth user, but now for some of Second Life participants as well. Tomorrow, there will apparently be a press conference from Germany where the first person (a woman born in China) who has accumulated $1 million real world dollars worth of virtual real estate will be making an announcement.