WordPress 2.6.5 has been released and includes a number of changes including one security fix, here is a list of the changes in detail:
- Added a check for the correct post_type to
blogger.editPostandblogger.deletePost(#8267). - Updates to
update_post_meta()anddelete_post_meta()to ensure they work correctly with post revisions and don’t create the meta on the revision instead of the post (#7925). - Protection for a very difficult to exploit XSS issue (#8291).
- Fix for an XSS issue with the Atom and RSS feeds on some hosting setups ([9754], [9770]).
For a complete list of all the changes you can read this section of the branches/2.6 log on the WordPress bug tracker.
Note that we have skipping version 2.6.4 and jumped from 2.6.3 to 2.6.5 to avoid confusion with a fake 2.6.4 release that made the rounds.
There is not and never will be a version 2.6.4.
westi on wordpress 
Thanks muchly for your efforts, I’m pushing the update out to a couple dozen blogs as I type this.
Is there a definitive guide somewhere for the exact procedure to perform an update to a WP-MU site?
I see different instructions in different places and am unsure exactly which pertain to single-site WP and which are for WP-MU.
We are currently running WP-MU v2.6.1 and have never performed an upgrade.
Sorry if this is a noob question. Thanks for any advice.
@Paul B: I would suggest you try asking on the WP-MU support forums or ask donncha himself.
I updated to 2.65 and suddenly it’s reverted back to the old dashboard… what happened?
Confused
@Yoganewbie: I am not sure what you mean by that. There were no changes to the dashboard in 2.6.5.
If you want to follow up on this you would do better to post on the http://wordpress.org support forums where I am sure someone will help you.
Thank You Peter,
I figured it out. There was just a loose nut on my keyoboard. LOL
I was using the 2.7 beta 3 and I went back to 2.6.5