Technically not Linux-specific as it is written in tcl/tk so should be cross-platform but the author developed it on Fedora Core 3.
It has a couple rough edges but works fine for backing up the scanner and entering new systems. Beats the heck out of doing it directly on the scanner and it is RadioReference download compatible.
It's not a 1-click install but if you follow the directions you should be up and running in a few minutes.
For updating firmware, just use the Uniden software under Wine. My thread on the subject from a couple weeks ago is here somewhere.
The serial protocol is pretty straightforward and available online from Uniden (you may have to register or something first). I studied it for a couple hours before getting my first script running. I wrote a couple programs in Python and a couple in Ruby. Nothing fancy but enough that I can edit a system configuration using vi and upload it to the scanner.