Though Ubisoft has recently released titles that only need a single activation as DRM, other games will be thoroughly disabled when Ubisoft moves their online servers next Tuesday, February 7th. This is due to their previous DRM that requires the game to be online at all times.
Online modes for the majority of Ubisoft games will be disrupted, with the exception of Assassin's Creed: Revelations and Driver: San Francisco for all platforms. Just Dance 3 on Xbox 360 and The Settlers Online on PC will escape the blackout too.
Unfortunately, Tom Clancy's HAWX 2, Might & Magic: Heroes 6, and The Settlers 7 for PC will go dark for both PC and Mac, the latter of which will also see Assassin's Creed, Splinter Cell Conviction, and The Settlers disabled as well. Uplay on PC will also be rendered inactive.
Ubisoft has yet to send word of how long this maintenance will take.