Spock differs from differs from recently launched WikiYou and other people search engines by using algorithms to find and merge the majority of their content into a unified profile. User generated content such (tags, links, photos) then augment the auto-generated content they spider from other sources such as wikipedia, IMDB, or social networking sites.
Note that competitor Wink seems to be moving toward a more automated model as well. They recently crossed 200 million people profiles and have been incorporating some of the same data sources as Spock.
A key Spock feature is a widget that shows results for a given tag (see embed below). Making the service public makes the widget a lot more useful. You can use it to make any number of lists around a how Spock ranks search terms. See, for example, the results for blogger and tech blogger.
Spock is certainly fun, and encourages user interaction by adding and voting on descriptive tags. It could easily become a definitive source of information about people. It will, however, likely take a massive number of page views to properly monetize the product – people searches do not generate the kind of advertising rates that ecommerce and other searches command.