Danah Boyd's Reality Check.
I hold back on commenting too much about Second Life because I risk descending into sarcastic sniping, so I was delighted to read Danah Boyd's seminal destruction of the hype.
"If you look at the rise of social tech amongst young people, it's not about divorcing the physical to live digitally. MySpace has more to do with offline structures of sociality than it has to do with virtuality. People are modeling their offline social network; the digital is complementing (and complicating) the physical. In an environment where anyone _could_ socialize with anyone, they don't."
Focus on the probable not the possible - it saves so much time.