More than 60 million people use Facebook Connect each month

"More than 80,000 websites and devices (including iPhone and Xbox) have implemented Facebook Connect since it launched in December 2008, says Beard. And more than 60 million Facebook users use Facebook Connect each month. And it’s not just a lot of small sites using the product. Two-thirds of comScore’s US Top 100 websites and half of comScore’s Global Top 100 websites have implemented Facebook Connect."
Source: Ethan Beard of Facebook, speaking at LeWeb, as reported by TechCrunch, 9th December 2009