I'm not sure I understand. I can drag a file from my file manager onto my Photoshop icon, and it will open the file in Photoshop. I have a stack of program icons on the right edge of my left-hand monitor for just that purpose. I think that's the opposite direction from what you're asking (drag the file onto the program, instead of drag the program onto the file) but is that significant?
-x16wda
there are two cases where dragging a node make sense.
hence you have a dock with bookmarks only and you have multiple accounts on the interweb. then it would come in quite handy to simply drag a bookmark node on the related browser window. while developing i very often have to check the same link in different browsers.
so instead of maintaining the same bookmarks in all browsers i would simply drag the bookmark from my central bookmark dock.
second case: working with lots of graphics or other often used documents.
some screenshot programs and programming tools have the functionality for dragging a finder on a target for further processing.