Quoted

Redstone Arsenal, AL (December 08, 2011) -- Today, the U.S. Army released America’s Army 3.2, which introduces the M106 Fast Obscurant Grenade (FOG) into game-play. With its short fuse, the M106 has the ability to air-burst, so players must throw it immediately. This fast exploding grenade creates a cloud of smoke to cover players’ actions, opening up many new strategies in the America’s Army game.

This release also marks the move of the game exclusively to the Steam platform for the distribution and authentication. Steam will allow AA users the ability to store up to 24 different Soldiers with unique names in the Steam Cloud and the ability to merge multiple AA3 accounts into one Steam account. It will also standardize the interface tools that are accessed via the client so all AA3 players will see same overlay and leaderboards.

The America’s Army forum has a full section of FAQs related to this move.

More info on new features such as the improved ladder functionality and new AA3 loader application, as well as other game-play changes, can be found in the SITREP.

Quoted from "Siroj"

how can i ever play aa 3 now? i only have downloaded 3.1.1
and someone know how i can have my AA2 account back?