Recently I've been intrigued by comments in one or two threads at the Ubuntu Forums concerning Ubuntu Tweak. Today, a couple of contributors to this thread suggested that Ubuntu Tweak can control changes to the login screen. If true, using this method would certainly be easier than the one that I recommended last May!
Notwithstanding my recent tweaking binge, I've neglected to change the dreary boot-splash and login window on my Karmic machine and the thread prompted me to give this power toy a trial run. Sadly however, the software failed to match my expectations; you can indeed change the login background and computer icon on the greeter, but (in Karmic anyway), your bespoke background is sandwiched between that same turgid Karmic background during the boot sequence.
So, I went back to the drawing board and followed my earlier instructions for changing the boot sequence background. Nonetheless, this is only a partial customization and the dull-looking simple-greeter (aka login window) still spoils the party; I was determined to find a way to brighten the login dialog. That's when I came across another excellent thread at the Ubuntu Forums outlining detailed instructions for customizing the entire boot sequence in Ubuntu 9.10. Authored by Towheed Mohammed, a .pdf version (58 pages) can also be downloaded from here.
The instructions are concise and accurate and Towheed's guide has enabled me to make some pretty natty changes to my login!