In this case, the metadata being used is a content label. Content labels are like the security certs you get from Verisign, except in this case the Content Labels are certifying that the site is conforming to web standards and accessibility rules. There are all kinds of Content Labels which a site could get to increase its trustworthiness.
The Content Labels can be assigned by and housed on the server of a trusted third party and then referred to in the metadata.
With Search Thresher installed a search of Google for “Tom Raftery” showing all sites yields the following results:
While the same search, but set to display only verified and self-labelled sites, only displays four results!:
This strikes me immediately as a great way to get rid of the scourge of splogs!
Also, when you select the verified and self-labelled sites only option, Search Thresher doesn’t display Google ads, unless they verify!
I recorded an interview with Paul Walsh, CEO of Segala, and published it as a podcast on PodLeaders.com earlier today.