As you are no doubt aware the latest operating system from Microsoft is Windows Phone 7.5 Mango, and apparently AT&T has now officially announced their Windows Phone Mango lineup by revealing 3 new 4G enabled smartphones featuring Mango along with the announcement that AT&T will update their existing WP7 handsets to Mango.

According to the guys over at Engadget the 3 new Mango devices are the HTC Titan, a device we have already heard about, along with two Samsung handsets, the Samsung Focus S and Samsung Focus Flash along with a little detail on both devices.

Specs for the Samsung Focus S are the handset will sport a 4.3-inch Super AMOLED Plus touch screen along with an 8 megapixel rear facing camera and 1.3 megapixel front facing camera, 1.4 GHz processor, 4G connectivity and 8.5mm thick and of course Mango.

As for the Samsung Focus Flash, the smartphone will pack a 3.7-inch Super AMOLED touch screen, 5 megapixel rear facing camera and a front facing camera of some description, and again a 1.4 GHz processor and Mango OS.

AT&T says, “With its unique user interface complete with colorful Live Tiles, the next version of Windows Phone, code-named Mango, puts people front and center making it easier to connect and share with friends, family and colleagues so important moments are never missed.”

Apparently these three Mango smartphone should arrive sometime in Q4 while AT&T existing Windows Phone lineup including the LG Quantum, HTC HD7S, HTC Surround, and Samsung Focus should receive the Windows Phone 7.5 update at some point “this fall.”