Earlier I commented about the disparity in numbers quoted for Second Life's population. It's not that any of the numbers are wrong - for what's being expressed, they're no doubt correct. Rather, it's a question of what's being measured. For my money, steady-state population, and those willing to pay for the experience are both fine metrics.
A recent LA Times article talks about a trend of some large businesses either reducing or eliminating their presence in Second Life. The article is short, insightful, and worth reading IMO. Some key quotes from that article:
My two specific longest-term motivations for being a computer scientist are making games and to enable some sort of global cyber space, not that I've done much for either of these in the last decade.
Where's the future of virtual communities and communications, and for that matter, is there one? I still think lack of a payoff for time invested in Second Life is its biggest conceptual challenge. World of Warcraft (WoW) has an incentive and reward structure built in, with social interaction as a side-benefit. WoW continues to do well, with more than 8.5 million subscribers, each paying more than $10 a month for the privilege.
World of Warcraft taps a large existing community - computer gamers - and offers an experience attractive to that community with significant value-adds. Perhaps the biggest challenge in Second Life is that the only existing community it really taps into are those who frequent online social mechanisms such as ICQ, MUD/MOO, and others, and press and the curious inspired by the press, who are no doubt a highly transient population.
I definitely want to see Second Life (or similar environments) succeed. It seems like they need to offer something else, though, in order to be anything more than a niche application.