One of many things I forgot to mention during the recent Xaminar was the Flights of Norway app and tutorial that Jonas Follesø (@follesoe) put together in 2011 - http://jonas.follesoe.no/2011/07/22/cross-platform-mobile-ndc-2011/
You can see the code for this in https://github.com/follesoe/FlightsNorway
It would be a good place to start if you wanted to think about rolling your own Mvvm framework.
It is definitely deserving of:
I wish I'd seen that code and talk before I started MvvmCross...
The video is on http://jonas.follesoe.no/ or embedded below: