Yum unhosed!

Well, I finally figured it out. Let me restate that. I resolved the problem. Whether I actually figured it out is probably open to debate. :-)

Here's my final post at the FedoraForum - and just in case it gets lost at some point:

rm -f /var/lib/rpm/__db*
rpm -vv --rebuilddb
yum clean all
yum update

By line:
1. Delete existing RPM databases.
2. Rebuild RPM databases (-vv = more logging than you can ever use)
3. Clean the YUM databases (not sure if this was actually required)
4. yum update now functions.

Yaay!