I don't have time for a full post right now, but I feel obliged to point out that, after a couple of theory chapters that are a touch uneven, Bonni Nardi has written a fantastic ethnography of World of Warcraft in her recently published book. I haven't finished, but her chapters on addiction and gender, for example, are balanced, articulate, and stimulating.
I'm enjoying this book a lot. Of course ... I would. :)