I've created a wiki page to gather thoughts on deskbar 2.18 (actaully not 2.18 specifically, just deskbar ideas). I've prefilled it with everything I could come up with, but your comments/input are most welcome!
http://live.gnome.org/DeskbarApplet/Ideas
As you will see we can't make everything on that page for 2.18. Not by a long shot. But let's get the ball rolling!