Sharp eyes will have noticed that the announcement did not contain any information's regarding support for EL. That was on purpose – we focused on getting RPM Fusion running, hence the EL branch (which was planed right from the start) did not get as much love as the Fedora branch. But the EL branch is in the works and some of the most important RPM Fusion packages have been built for EL already. Xine and xine-lib-extras-freeworld for example are available in the testing repository already; the AMD and Nvidia drivers are still missing, just like mplayer and vlc. But all of them should hopefully get into the repositories over the next few weeks.
You can already help testing the RPM Fusion packages for EL repositories by enabling it with this command:
rpm -ivh http://download1.rpmfusion.org/free/el/updates/testing/5/x86_64/rpmfusion-free-release-5-0.1.noarch.rpm http://download1.rpmfusion.org/nonfree/el/updates/testing/5/x86_64/rpmfusion-nonfree-release-5-0.1.noarch.rpm
Some of the RPM Fusion packages for EL require bits from EPEL, hence it's necessary that you have EPEL configured and enabled as well – just like you had to enable Fedora Extras to use Livna in the Fedora Core days. Just remember that the RPM Fusion for EL repositories are still in the early stages. Also not that you for now need to enable epel-testing, as some of the RPM Fusion packages depend on packages that are currently in epel-testing. That requirement should hopefully vanish with the next testing -> stable move in EPEL. The RPM Fusion for EL repositories of course don't replace and packages from EL or EPEL.
Note that not all RPM Fusion contributors have interest in building their packages for EL (just like not all Fedora contributors participate in EPEL). Hence we could need some help and people with rpm packaging skills that help getting the RPM Fusion repositories for EL filled and maintained. If you are interested contact me in private or (preferred) join the mailing list and just start to help.