Ty Anderson just shot me a link to MonoTouch (http://monotouch.net/), a product that allows you to develop IPhone software using Microsoft's .NET Framework.  You'll still need a Mac, the Apple iPhone SDK, and to be a member of the Apple iPhone Developer Program, but it's still pretty cool that it lets you use your current knowledge set to develop applications.  At least in theory.  Not sure how that works out in reality, but I'd be interested to see and hear if anyone has/is giving it a shot.