If you're not planning on respecting your own announcements, then don't make them at all. Swegabe posts once a week on Blogspot and is very transparent about the development process as well as when to expect the next update. It's not hidden behind paywalls and the release dates are typically a timeframe and not a specific date, i.e. "expect the new beta to drop this week".I personally don't care it takes long. Though the constant lying about the release date is that thing that pisses me off.
This is why a project manager is key to projects like this. They keep sh*t organized, take care of communication and kick project memebers in the a** when needed.