After a few days work I've installed Ubuntu 10.04LTS on a Pika Warp. Basic setup is 2MB Kernel, 250MB UBIFS on NAND, and 4GB SD Card.

The process was easier then expected; first time using UBIFS and had no major issue.

Setup included:
Mac G4 system
Debian 5.04 OS
Ubuntu 10.04 debootstrap
NFS boot

Next step will be to create a HOWTO documenting the steps required to setup a Warp. Once finished, I'll post the results here.