We'd been expecting the Mango update for Windows Phone to land "in the next week or two" and if an internal AT&T email leaked to WPCentral is to be believed, it should be available for some AT&T devices on September 27th.

The HTC Surround, LG Quantum, and some Samsung Focus devices are supposedly set to receive the update first, according to the documents. Why not every Samsung Focus? If you'll recall from some of the drama surrounding the "NoDo" update, there are actually two hardware revisions of the Focus -- 1.3 and 1.4 -- and only the 1.3 version is expected to get Mango on the 27th. The rest of AT&T's Windows Phone lineup should be getting Mango a bit later: mid-October for the HTC HD7S and late October for the 1.4-version of the Samsung Focus. Obviously we hope it all goes as planned: come Tuesday we'd love to fire up Zune Desktop, install the update, and get in on the multitasking action.

Source: WPCentral