Maybe because AMD don't officially support Fedora 13? Go ask them why - though at a guess, the response would be something like "our customers don't use it much". That of course refers to the fglrx drivers.
Originally Posted by Panix
There's probably hacks around to have it running on fedora anyway, if you look hard enough.
But if you're going to use a distro that AMD doesn't support, and is known not to support, and is known to stick to the packages available on their supported list (typically Ubuntu), then really you made that choice.