The easiest answer to putting Linux on a Beagle Board today is
Angstrom (http://beagleboard.org/project/angstrom) via Koen's pre-
built images (http://www.flickr.com/photos/jadon/2535894759/). He has
some newer images he mentioned on the IRC channel today: http://www.beagleboard.org/irclogs/index.php?date=2008-07-30#T11
:36:13.
Other options are certainly possible as some people have Mamona,
Ubuntu, and Debian running (Google is your friend). Pointers to some
ARM distros are at BeagleBoard: Distros for Beagle
.
http://eLinux.org/BeagleBoard is a nice place to get started with your
Beagle, after you have gotten comfortable with running the test kernel
on http://code.google.com/p/beagleboard.