A citation for http://flickr.com/photos/joshb/167490728/ using APA style, might look like this:
Bancroft, J. (2006, June 14). Second Life exhibit at The Tech Museum [Image]. Photograph retrieved from http://flickr.com/photos/joshb/167490728/Author: The creator's name is shown on the page.
Publication Date: For the publication date (shown in parentheses after the author's name), we used the date that the photo was taken, not the date it was uploaded. Both are indicated on the Flickr page, but the date that the image was created is more useful information about it.
Access Date: Not needed for APA style citations since this particular photograph will not change.