Microsoft employees have begun posting tweets that point to them testing the social network on Windows Phone 7.

Mango, the new update for WP7, has had Twitter integration planned since its announcement. Current builds of the new Microsoft smartphone OS feature slick Facebook functionality built in. Developers' builds of Mango however, are yet to include the Twitter functionality. 

Messages posted by the testers appear on Twitter as "via Windows Phone (via Windows Live)", confirming that the social network will integrate on WP7 handsets. Given that testing has begun now, it looks like things are on track for the Mango launch.

You can expect Mango to launch around September or October this year, with (fingers crossed) Twitter integration built in. Until then why not check out our extensive first look review of the soon to be released Windows Phone 7.5.

Fan of WP7? Or is it not your thing?