How Big is Second Life?

Linden Labs is quite open about their census of residents. You can find the latest metrics here, State of the Virtual World – Key Metrics, January 2007.
TechCrunch (recommended non-libray blog by uber-blogger Michael Arrington) offers these two stat-bites:
“Total registered users now number 3.1 million, up from 124,000 a year ago. A more conservative measurement of users that removes duplicate credit card and email information shows 2 million users, up from 95,000 a year ago. At any given time, ten to thirty thousand of those users are online and logged in to the world.”
“The total size of Second Life is growing briskly as well. The company reports a two week backlog in getting land up and running (this is effectively a hosting business, land=servers). There are 258 islands generating between $200-$300 per month each in revenue for the company, as well as another 103 square kilometers of mainland real estate, which costs $3-$10 per square meter. Based on straightline averages, this implies about $670,000/month in hosting revenue for the company.”
Growth was 23% from Dec 2006 to Jan. 2007.
Read the spreadsheet and get some insights into this newish world. You can find stats from the beginning about User Hours, Land Size, L$ Supply and User to User Transactions, LindeX Transactions, Population, Premium Residents, By Country, By Age , By Gender.
SL seems to be making a sincere effort at transparency on their user populations.
Stephen