We earlier talked about the expected features in WordPress 2.9 and the WordPress Trac where you can see the updates related to WordPress 2.9. Now WordPress team has released an official note saying that the WordPress 2.9 first beta for testing purposes will release by End of October 2009.
Here is the excerpt from the WordPress note:
We are aiming to release the first beta version of 2.9 around the end of October, once we have put the finishing touches on the new features, and then we switch to full on beta testing mode and your help and feedback will be very much appreciated. During the beta program will push out new builds for automated upgrades regularly and once we feel that a suitable level of stability has been achieves we will release a release candidate, and we hope to be able to make the final release 2.9 build available in either late November or early December.
Beta testing is done by different active users to fix some existing bugs and make the product bug free. The new features like Image Editing in WordPress 2.9 and other important changes really needs to be tested properly. It is advisable that you should install the WordPress 2.9 beta on test sites only as it is not the stable version yet.