Source of all software included is under GPL or other free license (MIT, BSD .... etc...)
Freely available from ftp.redhat.com
Red Hat EULA for RHEL 3 says:
Binaries obtained from Red Hat cannot be freely redistributed.
Red Hat logo and trademarks cannot be used without permission
Trademark Policy should be respected
“Title to the Software and any component, or to any copy, modification, or merged portion shall remain with the aforementioned, subject to the applicable license”.
And ... there are others: Fermi LTS 3.0.1, WhiteBox Linux, Caos Linux ....