iPhone SDK on Windows (alternative solutions)

I looked into this before buying a Mac Mini. The answer is, essentially, no. You pretty much have to buy a Leopard Mac to do iPhone SDK development for apps that run on non-jailbroken iPhones.

Not that it's 100% impossible, but it's 99.99% unreasonable. Like changing light bulbs with your feet.

Not only do you have to be in Xcode, but you have to get certificates into the Keychain manager to be able to have Xcode and the iPhone communicate. And you have to set all kinds of setting in Xcode just right.

You could easily build an app using PhoneGap or Appcelerators Titanium Mobile.

Both of these essentially act as a WebKit wrapper, so you can build your application with HTML/CSS/JavaScript. It's a pretty portable solution, too, but you are somewhat limited in what you can make - i.e, no intensive rendering or anything. It really all depends on what you're looking to do.

You could do what saurik of Cydia does, and write your code on a PC then build it on the iPhone itself (it is a Mac, technically!) after you jailbreak it. However, you don't get Interface Builder, so you're basically creating UIs in code by hand. It'd also be pretty tough to actually submit your app without a Mac.