On the PHPClasses.org blog they've posted the latest "Lately In PHP" Podcast - Episode #28, "PHP 5.5 Release Date and Plans":
PHP 5.5 release is already being planned. The release manager was picked, the new features are decided and the release date is estimated. This one of the main topics discussed by Manuel Lemos and Ernani Joppert in episode 28 of the Lately in PHP podcast. They also discussed the interpretation from VentureBeat that Zend is working on mobile version of PHP, using abstract symbol tables to optimize PHP further, and creating classes that provide APIs that are simpler for the users.