I have previously noted that I like the Western Digital My Book line of external hard drives (particularly for their design cues). However, since Leopard I have had some problems with my drive, in particular it would randomly unmount causing my SuperDuper! based automatic backup schedule to fail. Since I suspect some of our readers might suffer similar problems I thought it worth pointing out that Western Digital has finally released some updates. I've been testing them for a couple of weeks now and things seem to finally be working as advertised.
First there is a firmware update for the drive itself (be sure to pick your actual model) which is necessary for using the drive with Leopard. Second, there is also a Mac WD Drive Manager menubar application which is supposedly necessary for light and button functionality. In fact, the light "fuel gauge" on my drive still doesn't work properly, but since doing the firmware update and installing the drive manager I have not had the drive randomly unmount. So if you have been having problems running a My Book drive with Leopard I highly suggest applying the firmware update and running the Drive Manager to see if it helps.