Pretty edge-case, I realise, but:
Under OSX, if you move a file while editing it in most editors (eg TextWrangler), then hit save in the editor, the file reference is pointing to the new location.
In ST2, if I mv a file while editing, then save, the save goes to the original location. Likewise, if I mv a file then use OPT+click on title icon, the file is dis-associated.
This is a little bit contrary to the expected behaviour on OSX.
But it's still an awesome editor