Great tip, thanks! Can be used with Quicksilver's 'Run a Text Command in Terminal' to Quick-look files from anywhere.

How would you do this? I can't get it to work. If I find an image, say, I can't get 'Run Text in Terminal'
I tried a few different ways but none worked

I meant you could get an image file path in Quicksilver, put it into a command in the text window and run that using 'Run a Text Command in Terminal', without opening Terminal first (not so sexy).

However, I wrote a Quicksilver action that does what you're expecting, it's a little kludgy but it does the job:
http://db.tt/G7i1m3s

Put it in -/Library/Application Support/Quicksilver/Actions and relaunch Quicksilver. Find some images (different parent folders are OK), hit tab and bring up the 'Quick Quick Look' action. Typing 'QQ' works for me. It'll show your images over whatever app you happen to be in. Close the Quick Look window to bring Quicksilver back with the files.

One advantage of the last part is you can right-arrow into the selection again and re-select the files you want to use/trash etc.

Cheers, philostein.