When we first started playing Assassin's Creed, all the way back at the beginning of the first one, if you wanted to kill a man you usually had to stab him somewhere. As the series has progressed, though, we've slowly been given more and more ways to kill a man from a distance.
Knives, pistols and even a crossbow so good it bordered on cheating were introduced, opening up the way players can approach a given task in Assassin's Creed. The next game in the series, Revelations, takes this to an extreme (and deadly) conclusion.
Namely, you get hand grenades. They're called bombs, but really, they're hand grenades. And you can do a lot with them. The game world is littered with the ingredients you need to build a renaissance pineapple, and at work benches scattered throughout levels you can combine them to create custom grenades, which can stun, kill, slow chasing enemies or conceal the player.
If that sounds...strange, stranger still is the fact that throwing is aided by the inclusion of a guide line pointing out exactly where a grenade will land (even if you're bouncing it off a wall), and that like other ranged weapons in the series, if you toss one at a targeted enemy it will automatically find its way directly to his face.
In addition to explosives you can throw, there are also explosives you can plant, like old-timey versions of tripmines. These work like booby-traps, as Ezio can hide them on something like a dead guard, and when other guards arrive to investigate and move the bomb, it explodes killing them as well.
It would be easy to say this is risky for the series, or even bananas, but really, it doesn't make a lick of difference. Assassin's Creed games have always been about giving players a multitude of choices when tackling a mission, and all this does is give them one more. If you want to use it, great! If not, whatever.
I saw the grenades in action during a Gamescom demonstration (sadly hands-off), which aside from this new weapon was otherwise light on new details or information.