I think the grandparent post may have been thinking of this: http://www.sott.net/articles/show/223241 ('Dating' Site Imports 250,000 Facebook Profiles, Without Permission)
For the site linked in the parent post, it looks like the site uses the Facebook Graph API search function for public posts and then makes additional queries to show information about the creator of each post. Since you don't need a Facebook account to use it, I suspect they are making the queries via the server. They might be accumulating the profile photo data as they retrieve it, but it doesn't look any different than any other site that uses the server-side Facebook APIs.
For the site linked in the parent post, it looks like the site uses the Facebook Graph API search function for public posts and then makes additional queries to show information about the creator of each post. Since you don't need a Facebook account to use it, I suspect they are making the queries via the server. They might be accumulating the profile photo data as they retrieve it, but it doesn't look any different than any other site that uses the server-side Facebook APIs.