http://magiclantern.wikia.com/wiki/FAQ
Will it work on a 40D, 1000D, GH1, D7000, etc?
Short answer: Maybe.
Longer answer: The CHDK project successfully supports many different cameras running different operating systems, but finding the necessary kernel entry points is a very time consuming process. Since Magic Lantern is publicly available, someone with the time, the hardware and the inclination to port it to other cameras can do so.
The 40D, 450D, 1000D and 5Dmk1 are similar in hardware, but they run vxWorks and would be lots of effort to support.