Drobe today learnt that another Open Source Operating System was to join the ranks of Operating Systems available to run on ARM hardware. In the existing line up are ARMLinux and NetBSD, with the newcomer being OpenBSD.
Porting an OS to an entirely new processor is a huge job, but hopefully they'll be able to build on some of the work from the NetBSD/arm work. The initial machine being targetted is Simtec's StrongARM CATS board, a stronghold of much NetBSD/arm development. Hopefully we'll see other architectures in the future.
The port to the CATS board was begun in January, and it naturally has its own webpage.