Is there any mailing list, or notification that an implementer can sign up to watch for module releases since not all are posted here on Talk
Not to my knowledge sadly
Once more modules publish omods to Bintray you will be able to get notifications. See the watch section at https://bintray.com/openmrs/omod/openmrs-module-webservices.rest
We are working on providing an easy way to release omods to Bintray from the SDK. Once that is done, we’ll configure our CI to do it for every module release from our CI, which basically means all Reference Application modules will be there.