WordPress 2.9.1 Beta 1 is now available because the recent 2.9 release triggered a bug in certain versions of PHP’s curl extension.  With these versions of curl, scheduled posts and pingbacks are not processed correctly.  To fix this problem as well as a handful of other, lesser issues, WordPress Dev Team Members are quickly releasing 2.9.1, the first maintenance release of the 2.9 line.

The easiest way to test Beta 1 is to install the WordPress Beta Tester plugin, elect to get on the point release development track, and then perform an automatic upgrade via the Tools->Upgrade menu.  You can also download the Beta 1 package and install manually.  Fourteen tickets have been fixed in 2.9.1 Beta 1.  The curl problem and a couple of other problems are dependent on specific hosting configurations.