Ben Vanik has begun work on an Xbox 360 Emulator. Currently, it does nothing but some XEX print outs, but the immense amount of time and research put into this project is amazing and shows that 2014 will be a great year for 360 emulation.
If you have a GitHub account, you can star this REPO and watch as development progresses. Its open source, as you probably guessed. Whats even more interesting is that Ben's previous jobs include working at Google and Microsoft.
The goal of this project is to experiment, research, and educate on the topic of emulation of modern devices and operating systems. It is not for enabling illegal activity. All information is obtained via reverse engineering of legally purchased devices and games and information made public on the internet (you'd be surprised what's indexed on Google)- Ben Vanik
Find out more at Ben's Github: https://github.com/benvanik/xenia