nvidia does not support testing/beta operating systems. Also this is a kernel feature that is not enabled by default in other distros. Once Fedora Core 2 Final is released im sure that nvidia will have a driver release follow shortly there after. While it is not convienant for testers this is a test release for a reason. The Fedora Devel team says that things will be broken and this is not for normal use. In this case the nvidia driver is broken on their custom kernel. I recomend you download the latest source from www.kernel.org
and just make a new kernel and you will have a nice running system.