Joystiq has shared a lot of gameplay details on Destiny. Most interesting aspect of it all is that the game requires you play in groups of at least three.
The main campaign will require your three person team play together, and multiplayer modes will of course have you fight with even more players, who will also be in teams. Remember, Destiny’s design is such that you don’t fight against each other, but all player characters work together.
It’s a dramatic break from how online has been done so far, and of course, makes a lot of assumptions about the online capabilities of its players. We’ll see if there are enough players with good connections to make it a good experience for everyone.