Mark Zuckerberg describes Facebook as a service designed to help people communicate better, primarily through the social graph, which is the network of connections and relationships between people.
The social graph, he said, is the reason Facebook works. The popular social applications, such as Flirtable, FunWall and SuperPoke, built on the Facebook platform, are only a small part of Facebook's bigger ambition to help people communicate better.
In fact, Facebook is on a collision course with the more mature Web colonies--AOL, Google, Microsoft and Yahoo.
One of the key metrics of a major portal is stickiness--the number of applications used per member and time spent on the site. Communications services, such as e-mail, instant messaging, group chat, and forums, have proven to be very sticky.
Facebook is about to introduce a basic chat service and have some rudimentary e-mail capabilities. While Facebook executives have been cagey about specific plans to build more capable communications applications, they will evolve to be competitive with what AOL, Google, Microsoft, and Yahoo offer.
I would also expect Facebook to include Web search that takes advantage of the social-graph concept. For example, Facebook could implement a search for friends that also surfaces public information about them from the Web, or Web search results, that factor in what friends in an extended social graph click on for similar queries.
Facebook may even take on Google, possibly working with investor Microsoft, to deliver a comprehensive search service with a social dimension. Facebook could also acquire or partner with one of the semantic search start-ups, such as Hakia and Powerset.
Monetizing billions of pages and applications is part of developing a huge Web footprint. While Facebook has an ad deal with Microsoft, the company is developing its own socially aware ad technology, which is critical for extracting the full value of its network. The big players have all pursued a similar strategy.
AOL recently announced its acquisition of social network Bebo for $850 million in cash. The company has Web mail, instant messaging via AIM and ICQ, and a search deal with Google.
Google started with search and has expanded out to e-mail, IM, and a suite of productivity applications. It also spawned Orkut, a fledgling social network popular in Brazil.
Yahoo started with a directory, and later discovered e-mail and instant messaging, but it hasn't yet made its social-networking play, other than an attempt to acquire Facebook. The company has given hints that it will use its massive e-mail audience as a pivot point for integrating social networking into its platform.
Microsoft started with e-mail via its acquisition of Hotmail and has added IM and a variety of other applications, but no social-networking application, with exception of its $240 million investment in Facebook (for 1.5 percent of the company).
Looking out a few years, Facebook could grow its membership from 67 million to more than 200 million unique users per month, many of whom might use the service at the exclusion of the big four.
Of course, the big four are not going to stand still while Facebook tries to steal their thunder. Several scenarios could play out, including one of those major sites making an offer Facebook could not refuse.