Apple yesterday released GarageBand 2.0.1 Update which addresses issues with duplicating tracks, playhead snapping to grid, joining software instrument regions on adjacent tracks, making precise adjustments to volume and pan settings, and converting Software Instrument Apple Loops based on drum sounds into Real Instrument Apple Loops.
It also addresses an issue where recorded Real Instrument regions may not properly adjust to changes in the project key.
More info and download (14 MB) link here.