This plugin is awesome! It will help you to start with Portable Class Library in MonoTouch, Droid, etc. Just couple clicks and you may have entire multiplatform solution with MVVM Cross. Good work Adrian!
Also keep in mind if you are interested in the Xamarin iOS and Android development that Xamarin doesn't support Visual Studio 2013 yet. They are still working on this. So any port Ninja to 2013 would be lacking this modules unless used via a unsupported hack of some kind.
I am putting the finishing touches to version 3.0.0 of the Ninja. This will include support for VS2013.
I am aiming to have a beta version of it available next week - if you would like to help test it (just the vs2013 part) that would be great.
The code is already open source on github.
Things are changing at a fast pace - let me know what changes you are thinking of - I may have them covered.
It would be best to add Issues to the github repository regarding changes.