There are lots of reasons for why we have chosen the Flickr API as our preferred image supplier. For one I love the easy to use API and we are particularly interested in the geo coding and places methods that could really benefit our community.
There is also lots of pre-exisiting PHP lib files such as ZEND and various Codeigniter libraries that will be able to interact well with flickr. We are also interested in using the swfuploader for a simple uploader to the flickr API.
Overall we found Flickr to meet all our current Beta needs and a great partner to use for future proofing. Expect to see full flickr integration at launch. Our new account will be http://www.flickr.com/photos/whaddado/, there will be lots of testing on this account over the coming months but eventually you will see user photos start to appear in here.