An estimated 30m people have tried Facebook Places

"About 30 million people have tried Facebook places, a single source who works with Facebook tells us.
Reached for a response to this number, Facebook rep Larry Yu told us, "[I] don't have any guidance to offer right now, I'm afraid."
Not a denial.
Anyway, our source's number sounds reasonable to us."
Source:  Business Insider, 29th October 2010