Assassin's Creed Revelations - New Ubisoft game from that "universe" will have his beta tests ONLY on PS3. It was predictible because Brotherhood - last Ubi game, has beta tests only on PS3 too.
Beta tests will have only a Multiplayer game, and only available for PS+ and Uplay Users. Beta will be available for that users from 3rd to 11st September this year of course ;p
Demo version of game will be available only on consoles, so that's mean Ubi will not release it on PC :(