Social Networks, Information Economics, and Search
SNS has become a big enough field with sufficient internal dialogue that it's easy to forget that the promise of the whole shebang can be reduced to a single sentence:
Reducing informational exchange costs, particularly transactional search costs, through leveraging existing information exchange pathways such as personal relationships.
We're reminded of that singular purpose by a new SNS-driven search engine, Eurekaster. Danny Sullivan over at Search Engine Watch has a good article on this new twist on a major field.
And yes, Eurekaster, you should offer your service as a layer built on top of the Google API. That API is a fantastic tool for developers and experimenters; the fact that it acts as an innovation magnet for Google, by which the company can observe --> copy or observe --> acquire promising new technologies is just the price of the piper.