Most of you probably already heard of Xamarin. Their products allow to develop in C# for IOS and Android. The core of Xamarin is based on the Mono CLR, so although you will not have 100% compatibility with standard .NET code, must applications and frameworks should run with some minor modifications. If you want to know the effort needed to migrate your C# code to IOS or Android, you can try their .NET Mobility scanner (http://scan.xamarin.com).
I did the test by scanning Jace and discovered that a port to Android could be done with a limited amount of work. The release of Jace 0.8.5 is the result of this work. Due to limitations of Apple on IOS (no dynamic code), a port to IOS will take some additional time. But this is definitely on the roadmap for Jace.
You can find the new release of Jace at the usual places: