Good Evening,
as we did fonefood and some other services last year, we worked quite
a bit with the device atlas ruby lib. To make it slightly less painful
we bundled all the device atlas stuff we had into a plugin. We have
released it into the wild at github.com since a few days. If anyone
finds it useful, feel free to drop me a line.

http://github.com/lastminutelabs/acts_as_device_aware

cheers from apple wwdc, Mathias