It's supposed to be a better Dvorak. The keys are less of a departure from Qwerty than Dvorak's are so it's easier to learn, and it makes a few improvements over Dvorak. More on their website:
> Ergonomic and comfortable – Your fingers on QWERTY move 2.2x more than on Colemak. QWERTY has 16x more same hand row jumping than Colemak. There are 35x more words you can type using only the home row on Colemak.
> Easy to learn – Allows easy transition from QWERTY. Only 2 keys move between hands. Many common shortcuts (including Ctrl+Z/X/C/V) remain the same. Typing lessons available.
> Fast – Most of the typing is done on the strongest and fastest fingers. Low same-finger ratio.
> Multilingual – Allows to type in over 40 languages and to type various symbols, e.g. "pâté", "mañana", €, em-dash, non-breaking space.
> Free – Free software released under the public domain. You don't have to buy a new keyboard, just install a program.
