So the wraps are off on this one - Ubuntu will soon come to a ARMv7-based SoC near you. Here are the press releases from ARM and Canonical if you are into reading those.
I'm going to be adding support for several popular ARM-based devices to the Ubuntu kernel soon.
Please refer to my other post to get familiar with nomenclature in the ARM world if you need.
If you've followed Debian, they've had an armel port (ARM-endian-little), based on the new ARM ABI for a while now. A link to the excellent Debian EABI is in order for people interested in the nitty-gritty of ABIs. The Debian armel port is compiled for armv4t to support every ARM EABI-capable processor.
Ubuntu is going to concentrate on ARMv7-based processors, including the Cortex-A8 and Cortex-A9. In practice, that would mean bootstrapping the distro for ARMv5 architecture and then optimizing critical libraries and applications for the ARMv7 architecture.