Please read the archives of the Taroon list before launching any more FUD. There you will find that MySQL is also provided, just not supported.
Actually it's out of RHEL3-ES completely. I can't speak for the other distributions that they have.
No it's not. If you had a license you would know that both postgresql and mysql are available through the rhn channel for ES. Specifically they are both available in the "Red Hat Enterprise Linux ES (v. 3 for x86) Extras" suite of tools along with a number of other nice to have things like IBM's JRE.
Doesn't mean you can't compile and run it yourself though. It's more of a "we don't want to support it for this version" type of thing.
This however is certainly true and will remain so... bits are bits and if you don't have what you want you can certainly nab and compile it when ready!
-- csm Lunar Project Leader Disclaimer: "I am not a curmudgeon! No... really..." Addendum: "Bwahahaha! Fire up the orbital mind-control lasers!"