FYI there's a firmware upgrade available on the Garmin web site for Edge 605/705 devices.
From 3.10 to 3.20, June 14 2010

One item that caught my attention that I had questioned Garmin support about in the past, and ultimately requested as a future 'feature' is:

Backlight setting now saved to configuration and set automatically on power-on.

I've updated my 705 and will test it out tomorrow.

cheers
Jon