WordPress development team had a successful meeting on Sep 2nd, where they solidified their plans for WordPress 3.1. The team plans to release mid-December, preferably no later than Dec 15, so that the holidays won't interfere with the release. To that end, here's the current plan: "Oct 15th feature freeze, followed by a primary code freeze on Nov 1.
The beta period beings from Nov 15th at this point on, no more enhancements, only bug fixes, and a string freeze; translators rejoice on Dec 1st.
The esitmated final released date of WordPress 3.1 is December 15."
The finalized goals for WordPress 3.1 are "to have a short dev cycle, decent amount of testing time." Low on new features, heavy on ui and code cleanup, and avoidance of schema changes. Save the big ideas for 3.2 where we'll have the liberty to implement those ideas in PHP5. No schema changes and no big new APIs."