"Bungie, the developer behind the best-selling Xbox 360 franchise Halo, has revealed that it is currently hard at work on new IP alongside Halo 3: Recon, and that it is not limited by any agreement with Microsoft in terms of being restricted to particular platforms."
http://www.gamesindustry.biz/articles/bungie-our-new-ip-isn-t-tied-to-microsoft
A wii project?a PS3/360 project?who knows ?
but i guess this gen if it's not 1st/2nd party ,it will go multiplat.