Apple have updated GarageBand to v1.1 which addresses isolated performance and stability issues, allows per-track Echo settings similar to other effects, supports loop libraries in other disk locations, supports importing unprotected AAC audio files in addition to AIF and MP3 files, and addresses issues with ReWire support, moving GarageBand songs between different computers, Help support, fixing the timing of individual notes (as well as entire regions), and dragging entire tracks in the timeline.

New in v1.1:

* ReWire support.
* Rearrange tracks.
* Duplicate tracks.
* Rename tracks in the track header.
* Index loops in multiple locations.
* Convert Software Instrument loops to Real Instrument loops in the timeline.
* Fix the timing of individual Software Instrument notes in the track editor.
* Add AAC audio files to a song.
* New "Track Echo" instrument effect.
* Save a song as an archive.
* Close the song without quitting GarageBand.

More info at
http://www.apple.com/downloads/macosx/apple/garageband.html