Doctrine is a Object Relational Mapping and database abstraction
framework for PHP. The DBAL part of Doctrine derives from MDB2. The key idea was to provide very intuitive and easy-to-use persistency solution (eg. RoR ActiveRecord) with all the advanced features from the more heavy-weight solutions (eg. Hibernate).

Doctrine Query Language implements EJB 3 OQL specificiation and expands it a bit further (it has special LIMIT and OFFSET clauses).

Currently Doctrine already is propably the most advanced PHP DBAL /
ORM availible (http://www.phpdoctrine.net/doctrine/manual/features.php). There are still a lot of things that need to be done - especially regarding the documentation.

Doctrine has been developed for one year now. From the start it was clear the PHP community needs tools like this - the feedback has been very positive. Hopefully Doctrine can take one step further during the summer.