For those of us who miss being able to cut and paste in the Finder, I just found a pretty functional way to do it through Quicksilver triggers. Here's how:

1. Invoke Quicksilver (probably by pressing Control-Space)
2. Press Command-, to open its preferences
3. Go to Preferences » Application, and make sure 'Enable advanced features' is checked
4. Go to Catalog » Quicksilver and make sure 'Proxy objects' is checked
5. Go to Triggers and click the plus sign to add a new trigger and select Hotkey
6. Start typing Current Selection, and when the item pops up, press Tab
7. Start typing Move to... and then press Tab
8. In the last box, press Command-X clear the field. It must be completely empty for this to work -- no text, nothing
9. Click Save
10. Click the 'i' at the bottom right of the screen to show the trigger options
11. Under hot key, choose your preferred key command; I've chosen Shift-Command-X (see note below)

You're done! Select an item in the Finder, press your key command, then just start typing to move the selected file/folder to anywhere in your Quicksilver catalogue. Remember you can type '/' to access your computer and '~' to access your users folder from within Quicksilver.

Note: Quicksilver has a Scope function for the triggers which can limit the trigger to one app. In this case, the scope should be limited to the Finder. The Scope function, however, is broken under Leopard. If you're using an older version of OS X, you might be able to limit the trigger to the Finder and just use Command-X as the hotkey. Setting it to Command-X under Leopard, however, will break the Cut command in all apps.