When upgrading with yum I have started taking an rpm inventory before and after the upgrade.
Before Upgrade:

rpm -qa > BeforeUpgrade.txt

After Upgrade:

rpm -qa > AfterUpgrade.txt

Then I can compare them so that I know which packages were not upgraded and I can figure out why the did not upgrade.

cat BeforeUpgrade.txt AfterUpgrade.txt | sort | uniq -c | sort -n | grep "^\ *2"