After some network issues, I have just tried to get rpmfusion working but I keep getting a 404 error when running yum install or update. http://download1.rpmfusion.org/free/fedora/updates/12/x86_64/repodata/1fee0a13e20fc645e5035ab7cae70c9168d07b666bb37d04eaaf83bae0d2306b-primary.sqlite.bz2: [Errno 14] HTTP Error 404 : http://download1.rpmfusion.org/free/fedora/updates/12/x86_64/repodata/1fee0a13e20fc645e5035ab7cae70c9168d07b666bb37d04eaaf83bae0d2306b-primary.sqlite.bz2 I have tested with 12, 13 and 14. If I try to download the repodata files using firefox, I get a redirect instead of the repodata directory. I get http://download1.rpmfusion.org/free/fedora/updates/14/x86_64/repoview/index.html as an example instead of the repodata directory listing. To use Yum, I have to go through a web proxy and this may be causing the problem. I can get other repositories repodata via browser, just not rpmfusions. If I try to use wget to download the files, I also get a 404 error that it isn't found. I also tested with x86_64 and i386. I also tested with some mirrors and end up with the same problem.
I have been working on this and I cannot go any further on getting our corporate firewall configured to allow RPMFusion until I can test with a web browser and the various files in the repodata directories. I can get to the repodata via http://mirrors.cat.pdx.edu/ without the redirect. If I change the rpmfusion*.repo to use this site, I only get the firewall issue. If I try using the default rpmfusion settings, the repomd.xml files don't get updated so yum is also looking for the wrong files.
Closing due to inactivity - please feel free to reopen this if you're still having issues, although most likely there isn't anything we can do; RPM Fusion & its mirrors are online and as you mentioned the problem most probably lies in the your company's proxy configuration.