>"I think the problem is that photo-sharing services don’t allow you to easily provide copyright information,” said Sullivan, who operates SearchEngineLand.com.

Flickr's done that for years. The problem is with the social networks where photo-sharing is an incidental function.

>He thinks photo sharing services could offer users simple options like, "Would you be interested in selling images?" -- and could even act as agents for consumers.

Flickr does that, too.