The jointly developed [1] and award winning [2] PHP MVCstylish framework Okapi was released yesterday with the version number 1.0. Okapi is our preferred framework at Liip and local.ch for almost all new PHP based projects as its designed to meet our way of work and used tools. Therefore it fully supports XML/XSLT, AJAX, JSON, asynchronous front/backend communications, integration with 3rd libraries like Zend Framework and PEAR and much more. The core of Okapi is intentionally left pretty small but made easily extensible via so called extensions. It is released under the Apache Software License 2.0.
See the new Okapi Website for more information, it's quite extensive.
[1] Liip and local.ch were both involved in creating it
[2] Okapi-based projects won Best Of Swiss Web Technology Quality Gold twice in a row :)