'Andy's OSX Music Software' have released a greatly enhanced version of GRBand Assistant. It now includes the GB DrumLoops package. GRBand Assistant is a collection of software utilities designed to enhance the funcionality of Apple's GarageBand product. There are three software titles in this suite:

GB DrumLoops GB DrumLoops is a package which is capable of creating drum loops in the Apple Loops format ready for import to GarageBand or any other Apple Loops compatible application.
GB Import GB Import is a utility which imports standard exs files (as used by Apple's eMagic Logic package) into GarageBand as new Software Instruments.
MidiMaster Midi Master is a utility which uses information from a Midi file to play music through a sample based synthesizer, producing high quality sound through to your system's loudspeaker. It also has the capability to render the sound to hard disk in the form of an .aiff file which can be subsequently imported to GarageBand.

GRBand Assistant is Shareware and is available for US$15.00 from: http://andydrabble.users.btopenworld.com