folowing google's instructions
developer.android.com/.../device.html>

you need to reset permissions after creading the rules file:
chmod a+r /etc/udev/rules.d/51-android.rules

You may also need to create a group, specify it at the end of the line
in rules file, and add your user account to that group in Kubuntu.

As an aside, I'm not sure why those instructions have you entering the
vendor ID for a google device as well as motorola... I don't quite
get that.

As you are trying to figure this out, two programs to add to your xoom
that I enjoy very much on my usb-cripled droid:

andFTP
http://www.lysesoft.com/products/andftp/> allows to connect to ftp or
ssh server from device. supports secure/encrypted protocol
swiFTP
http://code.google.com/p/swiftp/> Runs an FTP server from your device
that can be connected to from any ftp client on a local network. can
be set up on the fly with dummy passwords and only runs when you
activate it.