Well, the title says it all. For example, if you select items 01.jpg, 02.jpg, 03.jpg in the Finder and then copy, the order on the clipboard will be 01.jpg, 02.jpg, 03.jpg. However, if you select 03.jpg, 01.jpg, 02.jpg and copy, you'll have them in that order on the clipboard. You can sort it anyway you want ... 1, 3, 5, 2, 4, 6, etc.

This is extremely useful for me. No more rearranging attachments' order in Mail.app, for example.

[robg adds: In prior OS X releases, this is how it worked in column view mode, but not the other view modes. In 10.5, it seems to work in all view modes, based on my limited testing this morning.]