From the Facebook terms of service: "By posting User Content to any part of the Site, you automatically grant, and you represent and warrant that you have the right to grant, to the Company an irrevocable, perpetual, non-exclusive, transferable, fully paid, worldwide license (with the right to sublicense) to use, copy, publicly perform, publicly display, reformat, translate, excerpt (in whole or in part) and distribute such User Content for any purpose, commercial, advertising, or otherwise, on or in connection with the Site or the promotion thereof, to prepare derivative works of, or incorporate into other works, such User Content, and to grant and authorize sublicenses of the foregoing."
English's not my native language, I may be overlooking a legal subtelty... but this looks like Facebooks takes the right to GIVE my pics, not to SELL them. As for "derivative works", is a generated thumbnail a "derivative work" of the pic I just uploaded?