OK - I must be really, really behind the times, having only recently learned about Second Life. Now even IBM CEO Sam Palmisano has an avatar in Second Life. It does look pretty cool and there seems to be another world going on out there, with 1.5M people joined up. Last night when I looked, there were 15,000 people online. I'd say that's a market to pay attention to. For me, I need to deal with my First Life before I can get into Second Life. :)
Palmisano Gets a Second Life - Yahoo.
Product Design Manager
Sam IBM in Second Life