If this feature is already in there, I've not seen it.
It would be great if there was a way to have a toolbar that had a field like there is in the start menu of Vista where a user could just start typing what they are searching for while the DOpus has perhaps a dropdown showing the results of what is matching. To add to this when the user hits enter that item would be launched.
I use this feature all of the time in Vista to launch apps. I simply press the Windows key and start typing part of the app's name I want to launch. A much better system of doing this is using a program in OSX called QuickSilver but on Vista MS's design is ok.
The way I would like to use this if this is possible is to be able to configure a hotkey that could bring DOpus up with the field enabled so that I can quickly begin typing the app or document I want to launch. This can also apply to directories where the lister would then immediately go to the directory that you had typed in and hit enter.
If you need further detail or a better explanation, let me know.