I've got my BeagleBone booting Debian 6 Squeeze!
(The real Squeeze, not Emdebian)
I've used the u-boot and kernel sources (with only a few tiny modifications from the am335x_evm_defconfig) from the Arago project git repos. I'm using multistrap and qemu-static to build and configure Debian on my amd64 host, then copying over the files to the microSD card.
I'll be sure to post more info on steps in the near future. The partitioning and formatting of the microSD card is the first step.
Click through the jump to see output in a Gist.