Orientation Island with all 700+ LSL scripts compiled to CIL, assembled in to CLR assemblies and running in the Mono VM embedded in the Second Life simulator. The Mono scripted birds sing and the Mono scripted hands spin and go "bing" when you touch them. There's still lots of bug fixing, optimisation and integration to be done, but it's looking good.
A couple of weeks later they posted an update with more screenshots:
Flying a mono biplane through a mono scripted Abbotts Aerodrome (in monochrome). All 2700+ LSL Abbotts scripts compile to CIL, assemble in to CLR assemblies and run in the Mono VM embedded in the Second Life simulator. Note that no source code was changed to make this work, the LSL source was just recompiled to run on the Mono VM.
This is pretty exciting. Am looking forward to help the SecondLife guys have a successful migration to Mono and assist them in exploiting the features of the Mono VM for their software.