What about supporting 64bit versions of - RHEL4; FC3; FC4; SLES9, SUSE10?
Also what about supporting RHEL3? A vast majority of companies already have RHEL3 rolled out and are very happy with it, and they don't see the need for moving onto RHEL4.
EDIT: Can you confirm if you will be supporting the soon to be released SLES10? Hopefully you can as it is based on SUSE10 similar to RHEL4/FC3