I'm liking just-released Fedora 14, but you might want to go 'pro' and wait for CentOS6, whenever they get around to it (basically a rebadged RHEL which also, just released a new version - 6)
Hmm, it seems CentOS don't do server releases, but Red Hat does a 30-day free evaluation release of RHEL 6. After that pricing goes
steep. It does have a ton of virtualization upgrades though.
EDITED: 12 Nov 2010 11:33 by DSMITHHFX