Yes, there are indeed development platforms on windows for the iPhone and iPad. The usually do not support the native iOS language: objective-c. However, most of them to allow you to build and or deploy onto iOS through some method or other. Here are a few recommendations:
DragonFire SDK. It is currently only for game development, but if you're really determined you can make a non-game app simply by adding UI elements programmatically (however this can be very painful). Dragon Fire SDK runs on Windows XP, Vista and 7. It costs a bit of money to be get full features from the SDK and submit to the AppStore. Here is the link: http://www.dragonfiresdk.com I have used it before, it works wonders. You can develop for the iPhone or iPad and it's all in C/C++. It comes with examples and help files too.
Stencyl. This is a simple and easy to use Game IDE that allows you to deploy your 2D games onto multiple platforms: Windows, Mac OSX, iOS, etc. STencyl requires no coding, however if you pay for the full version you can add your own objective-c or flash code. Here's the link: http://www.stencyl.com
Unity. Unity 3D is a very complex and very high end (in other words, expensive) game IDE and engine that lets you build 3D games for any platform (almost any, ex. iOS, OSX, Windows, Xbox, Wii, Playstation, Android, Linux). Unity costs (on the cheaper end) $1500... so this is probably not the best solution if you don't have the money to buy a Mac which is around the same price. However, if you're looking for one of the best Game Engines and IDEs with options to distribute to literally every platform, you may want to check it out: http://unity3d.com
All in all, DragonFire SDK is probably your best bet. It gives you the most flexibility on your PC for the price and it doesn't take a huge learning curve. I tried DragonFire before getting my Mac or knowing about iOS Development. And I had a simple guitar app up and running with DragonFire in an hour or so using my prior C++ knowledge.
If you aren't looking for a development platform, try out GNUStep to get a basic understanding of Obj-C. You could also look into building a "Hackintosh".
