This is licensed originally under the PHP license which is incompatible with the GPL.  However, I got explicit permission from the author (Andrei Zmievski <andrei@gravitonic.com>) on 18/12/07 to dual license it:

"I am fine with my library to be distributed under the GPL by Moodle project (which basically means that it's dual-licensed, as far as I can tell)."

-- Penny
