Fedora 18 is a truly stunning Operating System, but it has such a large bug I was dumfounded to find that it was a real problem and not something that I had done to bork yum. .rpms cannot be validated, and thus cannot be installed. There is a simple solution to get around this.
Use only yum's remote capabilities. This is an unattractive option since a lot of times software is not available in a repository (especially if it's hobbyist packaged).
Add the --nogpgcheck flag to yum, making the full command "sudo yum --nogpgcheck install package". This will disable checking altogether, which is what you want before the patch (which has already been submitted as of 1-16-12) is accepted and pushed.
About Recent Posts (blog related)
I'm sorry for the short "stubby" posts about Fedora tonight. I have had limited time to write this up, but I felt that it was critical. I got so fed up with it I nearly reinstalled Ubuntu. More workarounds to come.