I wrote about pca a few weeks back, and absolutely love the capabilities it brings to the table. To keep my servers up date with the latest security patches, I added the following cron job to extract security patches from the pca output, and E-mail them to my account:
0 0 * * * pca -l | awk '$5 ~ /S/ { print $0}' | mailx -s "Security updates for
$HOSTNAME" root
This works pretty well, and I now get E-mailed when security patches are available.