This may not help everyone (or anybody) who's having a yum dependency problem, but I thought I'd share just in case.

I recently ran "yum update" and was getting a bunch of weird dependency errors. The command that magically fixed everything was:

yum clean all

After running "yum clean all," I was able to run "yum update" with no errors.

From the yum man pages:

"yum clean packages"
Eliminate any cached packages from the system. Note that pack-
ages are not automatically deleted after they are downloaded.

"yum clean headers"
Eliminate all of the files which yum uses to determine the
remote availability of packages. Using this option will force
yum to download all the headers the next time it is run.

"yum clean all"
Runs yum clean packages and yum clean headers as above.