You were going to be able to use Flash CS5, but Apple is being tight now. Unity apps could probably be designed in Windows, but eventually You need the SDK to compile and run the app, and that is Mac OS only. You could make a Hackintosh partition on your Windows machine for now to test, if your PC is supported.
I saw this on another forum. I'm not a programmer, so I'm not sure if it's exactly what you were looking for but it seems to allow development on a PC. http://sio2interactive.com/SIO2_iPad_and_iPhone_3D_Game_Engine_Download.html
GameSalad and GLBasic both run under Windows. However, no matter what you still need a Mac to be able to compile and run on a real iDevice.
GameSalad Does not on windows. And they have no plans to make an windows version as understand it at their forum.
Really? I thought it was Windows for some reason. I never really looked into it so I just assumed it was designed as another Windows alternative.
You can try Dev using VMware, but u need a speedy PC and patience (it lags all the time). My first steps were made in VM but now I have Mac mini and it is such a difference...