Its hard to tell at this point how much ease-of use that these keyboards may have, but because of the general concept of adjusting to the spread of your hand they will be very nice. One thing about the concept that is great, is that you could purchase keysets for different applications and arrange them how you like. A generic FPS game keyset could have keys with pictures of inventory standard to FPS games, and movement keys shaped for ease of use. While a keyset for a photoshop type program could have keys for switching through layers, applying commonly used effects and toggling between things quickly. News.com has the full story

...an innovative configuration of movable "smart" keys that can be assigned macros, or keyword combinations, to accomplish tasks such as implementing game cheats or executing software commands. Customizing the keys' layout to your preferences and work style, the theory goes, improves efficiency and saves time--whether you're piloting a flight simulation or flitting around a spreadsheet.

Though I'd be willing to bet Z-boards would be one of the first to release such a keyboard to the mass market, as they already have the most customizable gaming keyboards available to the mass market. Though if you have the money to burn, the first models are available for purchase here- Ergodex.com

UPDATE
Toms hardware has posted a full review here