Xamarin 2.0 (updated answer)
Xamarin released its solution for this with Xamarin 2.0 (including iOS dev for Visual Studio 2010/2012). Like my previous answer below, installing Xamarin.iOS Visul Studio still requires a Mac as a remote assembly node, so for some it might be unlocking.
Disclaimer: Visual Studio support is only part of their "Business" license level , and it currently stands at $ 999 per year. However, they now have a free tier that allows them to deploy devices and an indie tier that is cheaper for Mac development.
I managed to get my system to work in beta between the Mac host and the Windows virtual machine. If you already have a Mac but prefer code in VS, this is a really good option.
Original answer
While you still need the Mac to run / debug projects, which sounds like it would be a break for you, this Visual Studio extension is created so you can write and compile MonoTouch projects in Visual Studio 2010.
MonoTouch for Visual Studio 2010
This is mainly for those who want to maintain experience with the IDE during development for MonoTouch, avoiding the learning curve of new keyboard shortcuts and single-panel development. When you get something compiled just fine, you will need to transfer these MonoDevelop source files to Mac for any debugging of the simulator or device and any packaging for deployment.
Disclaimer: even after completing all the steps on the project page, I could never get VS 2010 on 64-bit Windows 7 to correctly recognize the type of project. I planned to work in VS 2010, allowing Dropbox to sync files between my Windows machine and Mac, where I would do the final testing.
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