Ok small group of me and some friends want to dive into iphone development. (we have software experience) We are trying to do this the right way (investing the money in apple hardware plus the software we need.) We also want to port the software to other mobile markets (android / blackberry / windows). Does anyone know of a SDK that allows development and compiling on at least 3 of the 4 platforms?

we have looked at unity (UNITY: Game Development Tool)

Then we have also looked at esclipse but we arent 100% sure it allows for iphone game or application development.

Any suggestions or help would rock.

and any links.