TwitPic now take all rights on the images you upload to them. They can do whatever they want with the images you upload.
They have also signed with a british photo agence (WENN) to monetize the images.
Don't upload anything to TwitPic: They can use it commercially, without your consent.
See this article (in French): http://www.bluewin.ch/fr/index.php/1537,417125/Twitpic_vend_les_photos_de_ses_membres/fr/multimedia/infos