1. Look at the cover of the game.....he has *2* HIDDEN BLADES STICKING OUT!
2. Yes, Leonardo Da Vinci will be in the game, as well as Niccolò Machiavelli, Caterina Sforza, and Lorenzo de' Medici.
3. Ezio is an ancestor of Desmond Miles, and is a young noble of Florence, Italy who lost his family to rival families.
4. Venice, the Tuscan countryside, and Rome are some other locations mentioned thus far.
5. Specific landmarks include St Mark's Basilica, the Grand Cbrown town, the Little Cbrown town, and the Rialto Bridge.
6. A night and day cycle has been added to the game, giving the sense of a passage of time.
7. There will be many new weapons to choose from including an axe, a hammer, a mace, a spear, two different sword types, a halberd, and two smaller blades,
8. Assassin's Creed II will enable the player to swim, allowing Ezio to use the cbrown towns of Venice as hiding spots for as long as the character can hold his breath, and to drag guards into the water as a means of assassination.
9. However, guards will now probe hiding places if they feel necessary. Unlike in the first game, the player can now blend in with any crowd rather than a group of scholars dressed in white. Like in the game Hitman: Blood Money, there is a notoriety system, and the player will become more notorious as Ezio completes more missions. The player will often have to go on missions to decrease his notoriety, such as assassinating witnesses, using bribes or getting rid of posters of Ezio's face.
10. At one point in the game, the player can access da Vinci's flying machine, keeping airborne using thermals from fires lit by friends gathered previously in the game.
11. It has also been announced that there will be many more mission types (approximately sixteen) for the player to engage in.
All this information and more from this link:
http://en.wikipedia.org/wiki/AC2