http://www.macworld.com/2005/02/reviews/duallayerburners/index.php

BTW - technically these are "double layer" burners - the DVD+R DL format is called double. The DVD-R DL format is called dual. The -R consortium claims they own the term dual.

Toast v6.0.7 supports double-layer.

At this point there really aren't that many dual-layer drives shipping... certainly none from LaCie, Sony, etc.