There is a Zippo wb skin that is 'official' and has permissions. There is also an nVidia skin floating around with permissions, as well. I did a DeviantArt cursor using the 'Fella' mascot and had to get permission for that. I believe the college wb skins were commissioned.
Yes there are several skins/themes/etc out thre that were specifically commissioned by the Company concerned, so they naturally have permission for logo use.
Generally corporate logo use would need permission unless it could be demonstrated there was an argument for incidental [fair] use. It's generally argued that adapting an Adobe PSP icon [for example] for use on a Dock program is 'fair use'.
Personal use is a no-brainer....it is only public distribution...use on a website...or uploading for others to use that may need prior consent...