After over a million downloads of WordPress 2.9 and lots of feedback from all of you, we’re releasing WordPress? 2.9.1.? This release addresses a handful of minor issues as well as a rather annoying problem where scheduled posts and pingbacks are not processed correctly due to incompatibilities with some hosts.? If any of these issues affect you, give 2.9.1 a try.? Download 2.9.1 or upgrade automatically from the Tools->Upgrade menu in your blog’s admin area.
Read more: http://wordpress.org/development/2010/01/wordpress-2-9-1/