Here's a short film about an interactive projection maped onto the facade of a castle. The crowd was able to grow orchids up the facade, feed pollen to its blossoms, and burn it all down by using theyre mobile phones as input devices. (ok, basically any red green or blue light source would have done the trick). Blender was used for all the modelling and animation, and also for the cut of the documentation video.
We used the Giants game engine for realtime rendering. I wrote a Blender exporter for this engine a while ago. The main reason I prefer it over BGE is because I love Lua game logic scripting and I'm getting into CG for shader code. Blender 2.49 was used for the modeling and animation of the realtime content (because I didn't jet adapt the exporter to 2.5). We also used Blender for the modeling and mapping of the castles facade.
I had some fun cutting the interactive documentation film in Blender 2.5, but failed on color corection and noise removal (it was badly lit footage) that's why a final color corection and nois removal was done in After Effects.