Hi Steve,
Linux kernel 3.12 and device trees are not yet supported here. For the moment we only support the kernel that comes with the officially distributed TI AM335x SDK (version 3.2).
For support on the 3.12 kernel and device trees please post your question to the Beagle community forums: http://beagleboard.org/Community/Forums
The new SDK, which will support kernel 3.12 is expected to be released at the end of Q12014.
Best regards,
Miroslav