By displaying or publishing ("posting") any Content on or through the Instagram Services, you hereby grant to Instagram a non-exclusive, fully paid and royalty-free, worldwide, limited license to use, modify, delete from, add to, publicly perform, publicly display, reproduce and translate such Content, including without limitation distributing part or all of the Site in any media formats through any media channels, except Content not shared publicly ("private") will not be distributed outside the Instagram Services.
Nice way to give your photos away for free. Picasa is the same. Flickr is good, full rights retained and you can sign up for Getty images to sell your stuff for you.
Twitpic is the same. They will tell you it is necessary...
