Is Facebook Like Google, or More Like Yahoo?

Here’s a very familiar story that we all know: A pair of college kids launch a directory of the Internet that grows to become the most visited site on the web and makes them very rich. Then a few years later, another pair of college kids start a search engine, laser focused on one goal: to become the only search engine anyone uses. That upstart search engine ends up blowing past the first company while they were off courting Hollywood, and indeed becomes the most popular site in the world…