So HA only updates when chef runs (every 15 mins or so)? And when nodes are deleted, I guess something else has to clean them from chef? You'll also have to add these hosts to monitoring config.

I implemented something similar with puppet/mcollective/SQS years back. Poor man's service discovery. Here are some other options that, if you can handle the complexity of running Zookeper (or similar), are probably a bit cleaner:

http://jasonwilder.com/blog/2014/02/04/service-discovery-in-...