Developers working with Xamarin MonoTouch have been stuck with developing on a Macintosh and working with MonoDevelop. This hasn't been a bad thing. The Apple iOS SDK only runs on the Mac, so this requirement hasn't been a major limiting factor in iOS development.
Unfortunately, .NET and C# developers are used to using Visual Studio. Microsoft has spent a lot of time, effort and money to make Visual Studio the premier software development tool in existence. Xamarin Inc. has heard from those developers who want to integrate Visual Studio with iOS development. On Feb. 20, Xamarin introduced Xamarin.iOS for Visual Studio. This plug-in allows developers using Visual Studio to write iPhone and iPad applications for the iPhone using the Microsoft .NET Framework and C#.