fantastic the new devonthink pro!!!
I’ve envied Together’s group icons.
Can’t I change my DT’s group icons in the approaching DT 2.0?
You didn’t try? 
Get Info on something in the Finder, click its icon and press Cmd+C. Now click on something in DTP 2 and get its info, click the icon, and press Cmd+v. Voila (or “wah-la” if you’re American)! You can do it in DTP 1 too.
I’m not sure why the group icons look so crappy when you do it that way… their resolution might be very limited. pokes the developers in the ribs There might be a better/higher resolution way of doing it.
kalisphoenix, I’ve just done it! very very appreciate 
but as you said, the detail(resolution) is kind of poor…