He’s no doubt on here but I think the initial platforms are iPhone and XNA.
As I mentioned elsewhere, we had a meeting which brought together 4 formative games companies* all in different stages of development and we already know about Dark Water Studios (signed up for the Steam beta! Yeoowww!) and Wee Man Studios. There’s a couple of others (Straandlooper, CanDo3D)
*the four were @johngirvin, @zero37, @conormcc and myself. :)
and here’s some photos from Thursdays event:
http://cimota.com/blog/2010/03/27/photos-from-thursdays-ingage/