Basically yes, Fedora is Red Hat getting free testing of features and when it's time to create a new RHEL release, they grab a Fedora release, set it in stone and work from that.

http://en.wikipedia.org/wiki/Red_Hat_Enterprise_Linux

Red Hat Linux 6.2 → Red Hat Linux 6.2E

Red Hat Linux 7.2 → Red Hat Enterprise Linux 2.1

Red Hat Linux 10 beta 1 → Red Hat Enterprise Linux 3

Fedora Core 3 → Red Hat Enterprise Linux 4

Fedora Core 6 → Red Hat Enterprise Linux 5

Fedora 12, 13 → Red Hat Enterprise Linux 6

RHEL trees are forked off the Fedora repository, and released after a substantial stabilization and quality assurance effort.

Which adds a quote from the Fedora Project:

Red Hat Enterprise Linux is a commercial enterprise operating system and has its own set of test phases including alpha and beta releases which are separate and distinct from Fedora development.

And on that page[1] it states that RHEL6 is based on a "Mix of Fedora 12 Fedora 13 and several modifications".

Sorry to be pedantic, but that's significantly different than the Slackware model. Maybe it's just PTSD; I fled from RH in the old days onto the path that led to Slackware, so any comparison makes me touchy.

[1] https://fedoraproject.org/wiki/Red_Hat_Enterprise_Linux?rd=R...