Legally, you can use Marmalade and develop the entire application on Windows but to actually
- deploy to a device
- publish to the app store
you need to pay to become a licensed Apple developer and own or at least have access to a Mac.
The only exception I know to this is that there's a commercial game framework called Dragon Fire SDK that claims to let you do everything from Windows by, I believe, basically building and deploying your game for you. I have no idea if the Dragon Fire thing actually works, how good their framework is, etc. but my gut feeling is that it looks a little shoddy.
So, you know, the bottom line is that if you want to write to iOS buy a Mac Mini and a KVM switch. None of these crossplatform frameworks are perfect. You will need to do lots of testing on a real device so even the do-everything-on-windows-with-marmalade-and-get-your-friend-with-a-mac-to-deploy-for-you-when-you're-done option isn't really realistic in my opinion. Maybe for a very basic game.