Need to read that at some point.
Tried to adopt this patchset but it was so far out of sync with master that it is not worth it for the changes that would be provided.
I've started some ironic notifications code on a hear-ironic-notifications branch of the ceilometer code. However at the moment it is basically a cargo cult of hearing nova notifications. There will be issues with munging the data that need to be resolved. I've asked the Ironic project for some input.