Although AT&Ts Mango update program has generally been quite successful, there are a few missing pieces: Samsung Focus v1.4, the Dell Venue Pro and the HTC HD7S are still missing.

Looks like that last one, the HD7S, may be getting Mango slightly sooner than expected. The original leaked plans aimed for an end of October ETA, but now it seems they may have wrapped up testing earlier than expected. WinRumors received an internal AT&T letter stating that the Mango update for the 4.3" screen device should be starting today.

From part of the letter that WinRumors received:

"On October 11, 2011, Microsoft is scheduled to begin rolling out the new Mango 7720 update to AT&T customers with existing HTC HD7S Windows Phone 7 devices. The update supports the same enhancements that began rolling out to AT&T customers using HTC Surround, LG Quantum, and Samsung Focus devices in late September."

Going to the official Windows Phone support page, we see in fact that the HD7S is in "scheduling" meaning a switch to "delivering" is easily done. However, the Focus v1.4 is still in testing and the Dell Venue Pro...well...

"The HTC HD7S is currently Scheduling, while the Samsung Focus v. 1.4 is Testing and the Dell Venue Pro is in Planning."

Hit us up if and when you get your official update. Heck, our own George Ponder will be flashing his ASAP.