It has taken the top spot from other location based services such as Gowola and Foursquare in little to no time.
It was obvious Facebook as going to be able to achieve such results with the huge user base they have on hand.
Also on the subject of Facebook, Facebook has made Chat upgrades and Upgrades to Facebook Groups
In a bid to give users more tools and control over the sharing of information (and perhaps preempt Google) Facebook introduced a new
way to create and communicate with small private groups of people. Through an API this same functionality will be extended to publishers and third
party developers like Facebook Connect is today.