The game will feature 18 levels, with three different stories and six levels per a story. Each level will include two-player, drop-in/out co-op play (off and online). The story centers around a break-out from Arkham Asylum and the Batcave will be the hub of the game.
Other interesting tidbits include:
Each story is playable from either the Hero or Villain point of view. (For example, in the aforementioned levels, you could also play as Catwoman trying to steal the diamond or as Batman trying to rescue Commissioner Gordon.)
There will be strictly vehicular levels in the game, although Doyle declined to say what they would be. (The press release states that the Batmobile, Batwing and Batboat will be available.)
As for the DS version: "It's not a port, it's completely done separately. It's done at Traveller's Tales by the same team that did the 'Saga' DS version, and they're a really, really good team. It's kind of the same but different, and there's a lot of touch screen in there." He declined to say anything about the PSP version.
Hit up the link for the full write-up and lots more details.