Johannes Schlüter, the new release manager for the PHP 5.3 series, has posted an update on the progress of the release including a brief list of the new things included in the update.
Since a few hours we're having, thanks to Edin, Windows snapshots for the upcoming PHP 5.3 release. In combination with the latest sources from CVS everybody should be able to test the current state.
Included in his list of updates are things like: namespaces, late static binding, the __callStatic magic method and the mysql native driver (mysqlnd). He also recommends that, if you're currently running something in the PHP 5.2.x series, you update to the latest on that before making the jump to PHP 5.3 when it comes out.