Actually, Lukas Smith(MDB2 creator) contributed a patch that replaces the Pear::DB code with MDB2, which I believe has all the features of ADODB and more. I believe Thomas has asked for someone to completely get rid of the rcube_db layer, and directly use MDB2 calls instead, so if you're familiar with the DB code perhaps you could try that?
how is this progressing? is there someone working on this?
i'm prepared to work on this, but i don't want to duplicate the work.
cheers justin