There is discussion currently going on regarding who owns photos uploaded to Facebook.
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 sub licenses of the foregoing.
Maybe Facebook is simply protecting itself to be able to display the users images in all kinds of ways but I think the terms are way too restrictive.
However other photo sharing services on the Internet get by with much less assertion over the users content.
If you are worried about this issue and would like to share photos with your friends on Facebook without giving them away to Facebook then the best way is to store the photos somewhere else and use various methods to make them available in Facebook.
You have several options depending on where and how your photos are hosted.
If you have your photos on Flickr, the MyFlickr application is very handy. It shows a selection of your photos on your profile page and when you update your photos on Flickr it posts updates to your news feed so that your friends are notified about it.
One can argue that Flickr (soon to possibly be owned my Microsoft 🙁 ) is another 3rd party that will hold your photos but their TOS are much less restrictive and they support Creative Commons license which is a great way to spread your photos while retaining some rights
Gallery2 is a popular software to host your photos on your own server. The Gallery2 Embed is a Facebook application that embeds a selection of your photos in your profile. If a visitor clicks on the photo, she is then taken to your own website with your photos.
One thing missing with “Gallery2 Embed” is that it doesn’t publish updates in your newsfeed when you upload photos so your friends are not made aware of any updates. I have grand plans to write my own Gallery2 Facebook application that will support updates in your newsfeed but lack of time is very prominent at the moment.
Some other popular photo hosting sites and the Facebook apps for them:
Picasa: Picasa Gallery Slideshows
.Mac: .Mac Web Gallery
DeviantArt: My deviantART
Photobucket: Photo Wall
SmugMug: My Photos from SmugMug
Good luck and make sure to remain the copyright holder of YOUR photos!