Many older clients, or clients using non-PXE methods like LinuxBIOS or bootp cannot use the standard kernel and initrd images. The kernel and initrd must be wrapped in a certain way to allow booting by these clients. Debian/Ubuntu has their own implementation using mkelfimage to support these clients that I need to adapt in a Fedora way. Some very older clients need an image wrapped with mknbi instead to be supported, but it is currently not a priority for me to implement this.
Changing version to '9' as part of upcoming Fedora 9 GA. More information and reason for this action is here: http://fedoraproject.org/wiki/BugZappers/HouseKeeping
Checked into ltsp-trunk and will be in the next ltsp update.