Ubisoft recently announced the details of a new system called the "Online Services Platform" and have provided a Q&A
which reveals the following interesting tidbit:
Is there an "off-line" option?
No. The added services to the game (unlimited installs, online storage of saved games and the fact that you don’t need the game disc to play) require you to have an online connection while playing the game.
The Q&A reads like a Bill of Un-rights for gamers. Clearly a piracy protection measure, this move simply makes it harder for legitimate gamers to play games they've bought, makes it harder for them to sell them in the second hand market - and presumably will do absolutely nothing to stop pirates anyway.