In the interest of making sure that the new policy is communicated to everyone, here's a short summary:
- We are planning a focused, 100% backwards compatible "Plone 3.1 release":http://plone.org/products/plone/roadmap#3.1 sometime early 2008.
- The next major release (formerly known as Plone 3.5) has been renamed "Plone 4.0":http://plone.org/products/plone/roadmap#4.0 to make it clear that it's a bigger effort with larger infrastructural changes.
The dates for both Plone 3.1 and Plone 4.0 are still tentative, and they are both accepting improvement proposals (PLIPs) at this point.
By making this change, we can release smaller, incremental x.1, x.2 releases that aim to be 100% backwards compatible with products working on the x.0 release in that series, and reserve the more fundamental changes for the next x.0 release.
For the full summary of the discussion leading up to this, see the "original discussion on version naming":http://www.nabble.com/Proposal-for-the-coming-Plone-releases-tf4577934s6745.html on the mailing lists. It also contains some suggestions on what would and wouldn't be acceptable in a minor release, using Plone 3.1 as an example.
There's no big change to how Plone releases are done, this is just to make the version naming clearer, and to make sure the roadmap makes sense to casual observers.
We hope that this lets version numbering be closer to the intuitive understanding people have, what can and cannot be expected to work together when it comes to third-party products, and better communicate what the upgrade expectations should be.
On behalf of the Plone Team,
— Alexander Limi