If you do have a fat PS3 with later firmwares (current is 3.55) then you will need to downgrade with usb dongle (or equivalent like psfServiceMod for some HTC phones).
You can also wait for the promised AsBestOS hack that should bring back OtherOS style support to the current firmwares.
So it was a cool hack until Sony decided to remove OtherOS support to avoid hacks (and this did not worked as expected for them...).
From what I heard from an Ubisoft employee, AC2 and Silent Hunter were not using the full potential of the DRM scheme because it was added late in the dev phase.
For Settlers 7 it apparently uses it fully: most of the game economics processing is done on the server. A crack is still possible but that would mean recreate the economics engine completely by analyzing the answers from the official server.
Very sad DRM, I already stated to this guy that I wanted to buy AC2 to play it but that I will not (and I won't pirate it either). I just consider Ubisoft games as non existing until that crazy DRM is removed (which won't happen I guess).