There are a lot of howto guides on getting Ubuntu running on the
Beagle Board, but having recently got it all up and running from
scratch, I've put together a guide that may help other people who are
completely new to the platform - Ubuntu included.
I'm running on a Mac, so I went down the track of setting up an Ubuntu
virtual machine using VMware Fusion - if you don't have Fusion, you
could use the excellent, and free, VirtualBox from Sun:
http://www.virtualbox.org/
I've outlined exactly what needs to be done, from the initial
installation of Ubuntu in the vm, through to formatting the SD Card,
installing the image built with rootstock and configuring the beagle
board to default to boot from flash.
I hope these instructions are helpful to others:
http://automatica.com.au/blog/2009/10/howto-ubuntu-on-the-beagleboard/
If anyone has any comments, or there's anything in the guide that's
not clear, please let me know and I'll update it.