The 5D mark II for which it was originally developed could hardly be considered low end. The official firmware at the time was just extremely lacking for film makers. (it's only very lacking these days).

Unrelated: Trammell Hudson, the guy who started Magic Lantern has done a lot of other interesting stuff - such as open source helicopter control software.

I was referring to the support for other lower-end DSLRs like the 550d rather than the 5D mark II, although I didn't know it was originally developed for the 5D mark II, thanks.