Lion introduces a long-requested 'copy and move' command in Finder, similar to 'cut and paste' in Windows Explorer.
To move files in Finder first press Command+C to copy the selected files, then press Command+Option+V to move the copied files to the current folder.
[crarko adds: And the Finder menu item changes to 'Move Item Here.' Makes a lot more sense from a UI perspective than Cut and Paste. And it's not likely to happen by accident. Nice little touch.]
Mac OS X Hints