I have seen a few rumblings of this on other sites but nothing with any real solutions. I have seen gpk-prefs but not sure exactly how that will let me know that my server has updates available. Perhaps this is something baked into RHN that I am not seeing. I get one-off notifications about patches, but that's not what I want. I want a to be notified at X interval about all the security-only patches available on XYZ system. I suppose I could cron this but am guessing RH has thought of this already. Thanks a lot for any ideas.

Have you searched the red hat knowledge base ?
https://access.redhat.com/knowledge/search

your RHN id will be needed .

I did check out the KB. Not much luck.

I wrote a simple script to plug into Nagios in the meantime. I have a broader question about patch management but will start another thread for that.