I don't know if anyone has seen this video from ipodtouchmaster.com or not.
How to Get SummerBoard to work in 1.1.3 on iPod Touch+iPhone
I just finished jailbreaking my 16gig iPod Touch to 1.1.4 from his videos, and have just run into the same problem everyone else was having with the SummerBoard themes showing up in the list, but not actually displaying anything. Now even though this video is for a 1.1.3 jailbroken firmware, this actually worked on mine without having to download any of the summerboard fixes from Installer. If you know how to run an OpenSSH program, I use WinSCP, you have to change the permissions under:
Systems/Library/CoreServices/SpringBoard.app
Then when you get there, you have to select all of the files NOT in folders, highlight EVERYTHING, NOT in a folder. Then right click, and go into properties. The permission code is 755, you will see a little box where you can type this in. click ok, and it will do it's thing, then restart. Check out the vids, I found them helpful.