In reply to melmyo:
> People don't have to be registered on either, unless you set your photos to be viewable by friends & family only, or private.
Not so with flickr, you can make photos private, only viewable by friends/family etc but send a 'guest pass' to non-flickr people for them to view the photos which can be cancelled at any time.
> There has also been a lot of bad press about people stealing photos off flickr, but not so much (infact none that I know of) from facebook.
But then you do ".... grant Facebook an irrevocable, perpetual, non-exclusive, transferable, fully paid, worldwide license (with the right to sublicense) to (a) use, copy, publish, stream, store, retain, publicly perform or display, transmit, scan, reformat, modify, edit, frame, translate, excerpt, adapt, create derivative works and distribute (through multiple tiers), any User Content you (i) Post ..."