I have just finished creating a FC11 LiveUsb on a 18G SDHC card with the following charactaristics:
4G persistent overlay
4G persistent home (un-encrypted)
I had to modify the 'livecd-iso-to-disk' script to get the 4G sizes for the overlay and home (my sdhc is formatted FAT32). My notebook that I use for testing has a broadcom 4306 (rev 3) wireless card, so of course that initially did not work. Applied the offline rpm offered at the dnmouse page, and got the wireless working. Originally, I tried to apply the 'online' fix for the braodcom, but was not successful (It completely hosed my network devices).
I disabled the auto login of 'liveuser' by editing the /etc/gdm/custom.conf script and removed the liveuser user account. I also wrote a script for applying system updates that first makes a backup copy of the overlay, so that in event of a caused by the update, the backup copy can be copied back to the proper folder. It the invonkes 'yum upgrade'. Making a copy of the overlay file still leaves me ~2G for misc. files that I may want to keep and have access to globally.
I probably could have (an may in the future) have created the home overlay smaller (let's say ~2G). I wanted the persistent home to keep things that I have no need of globally.
So far, so good and I am pleased with the result.
J. L. King