The Greenhouse officially opens up to all users in April so any implementations of greenhouse items before then would be coincidental. After the roll out there should be a release schedule 'rough in' associated with top greenhouse items that are scheduled to make implementation, so we should see some dates within the post.
I noticed in our beta for the current PPM release that there is a roadmap type link in the User dashboard after logging in that provides better indication of things to come. Our release notes will still be available just prior to implementation as a download from the login screen.