Henry Hayes has a recent post to his blog looking at a the change for the user agent support for the browser detection functionality in the Zend Framework.
Recently it has come to light that Zend Framework are dropping support for the WurflApi Features Adapter in the Zend_Http_UserAgent component. This is due to licensing issues. As of version 1.12 Zend_Http_UserAgent_Mobile constant DEFAULT_FEATURES_ADAPTER_CLASSNAME now specifies that Zend_Http_UserAgent_Features_Adapter_Browscap is now the default mobile adapter.
He shows you how to get the browscap support set up and configured for your PHP installation and what needs to be done to a pre-1.12 ZF release application (using this library) and in a post-1.12 application (almost nothing).