At the main menu enter Circle, L2, X, square, triangle, R2, L2.
Infinite eagle vision:
After finishing the game, you can use Eagle Vision inside the Animus.
Slaughter without penalty:
After finishing the game, you can kill anyone inside the Animus.
Destroy a market stall:
Grab a citizen and throw him into a market stall from the side. The stall will collapse on top of the guy inside the stall and kill all people surrounding it.
Loud assassination:
Hold LB + RB and press X when approaching a guard.
Silent assassination:
Hold LB and press X when behind a guard.
Conference room:
After the credits show up at the end of the game you'll receive an access code for the computer at to the Animus. Once you crack the computer, you'll see an inbox, outbox and deleted message. Look at the inbox and select the entry regarding the conference room. Now you can go to the conference room and access it with the keypad.
Accessing computers:
There are three computers, two in the main room and one in the conference room. To access Lucy's computer, go to the computer on the anumus and pick up the pen beside it. To access Vidics, steal the pen that is in his pocket when you see him earlier in the game. Read all emails on both computer including the ones in the deleted section. After reading them, you can access the computer in the conference room.
Escape guards:
When being chased by guards, go to a high roof and kill the guards that appear. After you kill a few guards, they will give up.
Easier game completion:
Complete these in the following order to decrease the difficulty of each major assassination and lower the time needed to complete the game.
1. Visit Assassin's Guild.
2. Scan the city by first climbing all of the view points.
3. Rescue all citizens from the thugs.
4. Complete all of the informant's missions
5. Pickpocket the shysters in all of the pickpocket missions
6. Go back to the Assassin's Guild and get ready for the major assassination mission.
Source:http://www.gamingcheats.com/ps3/10522/assassins-creed-(limited-edition)-cheats.html
