With my 60gb player confirmed to be shipping, I am going to be moving my music to it before selling my existing player to a friend. I also don't want to loose the plays data built up on my player, since I discovered it was keeping track since day 1, and that has been useful lately with the different weighted shuffle modes.

How can I back this up? I assume it's part of the scratch space on the first drive. What will happen if I use dd to move it to the new player? Will it see it as valid data as long as I also move my music, or will it discard it?

If you've directly copied all the music (i.e. if all the FIDs are the same) then yes, dd'ing /dev/hda3 from one player to the other should copy all the play-count information (and the EQ presets and the tuner stations and the bookmarks).

Peter