Microsoft's app for its instant messaging service Windows Live Messenger is the second most popular app on Facebook, according to figures from AppData. An average of 9.1m users accessed Microsoft's app every day in the first week in November, making it the fastest growing app in terms of actual users. The growth follows the latest release of Windows Live Messenger, which includes deep integration with Facebook and Facebook chat. Microsoft is rolling out the feature slowly in order to avoid performance issues, and claims that currently just 20% of Messenger users have access to the Facebook integration. So far, the firm says it has hosted 250m chat conversations between Messenger and Facebook, adding up to 1.5bn minutes in total.

Despite Messenger's impressive growth, Zynga's FarmVille Facebook app remains the most popular with 16.6m daily average users in the first week of November. Other games in AppData's top 10 include Texas HoldEm Poker, FrontierVille and Café World.