In response to several other posts lately about the PEAR::DB package in PEAR (and things that could be done to improve it), David Coallier got a bit fed up and shared his opinion - "PEAR::DB is deprecated, got it?"
All new features are made into MDB2 and not DB, the only thing that is being done on DB is security fixes. So MDB2 is first of all, faster, smaller (Because of it's driver and modularity), easier, and has more features (LOB handling, Iterator, etc) and better end-user documentation, quite solid docs indeed.
Of course, the comments of the post are full of people arguing to keep it around and others that agree with David, especially in light of a MDB2 driver for the Zend Framework he mentions.