FoldingLayout ported to Xamarin.Android29 Apr 2014 | Xamarin.Android
Find it in Xamarin Component Store and fork it on GitHub!
Here are some sample screenshots showing what it can do:
|Folding Horizontally with 2 folds
It also has implementations which sub-classes DrawerLayout and SlidingPaneLayout, from Support v4, which adds the effect to their drawer/pane.