If they are using sophisticated algorithms, then they are using them behind the scenes. For example, such a startup might use sophisticated spam detection or a clever algorithm to get a performance boost.

This is different from a startup such as Google where PageRank is major breakthrough that is made obvious to everyone. We don't see many startups like Google in web 2.0. It seems that web 2.0 is more about harvesting people power and less about sophisticated algorithms.