> Is RHEL ever really a snapshot of Fedora?

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