I have an idea. I don't know if it will be hard to integrate, but here it goes:
I have tons of friends on facebook that upload their photography through there. I was wondering if there was a way for them to connect with my site and transfer their images over to my site. Is that possible?
I knew when I was creating this mod I was opening up a can of worms

I think the answer is yes, it can be done, but not sure. I compared other gallery scripts (not 4images) and I found a couple of tries at it and I guess it is working for them.
Looking at the API calls that you can make to facebook, it should be possible.
Looking at Facebook's policies...
http://developers.facebook.com/policy2.You may cache data you receive from the Facebook API in order to improve your application’s user experience, but you should try to keep the data up to date. This permission does not give you any rights to such data (including the right to transfer) absent explicit consent from the users who own the data.
3.Users give you their basic account information when they connect with your application. For all other data, you must obtain explicit consent from the user who provided the data to us before using it for any purpose other than displaying it back to the user on your application. A user’s friends’ data can only be used in the context of the user’s experience on your application.
It looks like you are able to pull images from your own account, not friends or groups unless you are the owner of that photo as long as you have something posted on the 4images side that the user gives consent to do so and Facebook is also wanting in their policy for the user to be able to quickly and easily remove the images from your site if they choose to.
My vision of how this should look on the 4images side would be...
when the user is in a category that they have rights to upload to there would be an extra button at the top 'import from facebook album' and then they would see a list of their albums and then a list (thumbnails) of the photos in the album to choose from and then import them.
On the flip side, maybe a button on the details or lightbox page that has 'export to facebook album' and kinda doing the same thing.
Is that what you had in mind?
It sounds like an interesting adventure for the next version of this mod. I am already working on a way to track the likes/shares per image so you can have them on your TOP page like the ratings and downloads so I will add this to the list.
I will be honest, I am not on the computer much in the summer, computer room is 100degrees with 90% humidity, so I am on my computer very little till the heat passes so don't expect this to happen overnight unless someone else wants to take it on...
If anyone has any other ideas for the facebook integration, now would be a good time to ask...I will post if I was successful or not when I get to that point.