Facebook will be launching a major redesign of their profiles in the near future. As always, users are flipping out. I think that Facebook has figured out precisely what they need to do to avoid becoming another MySpace.
From the late 1990's up to the Facebook/MySpace battle, we saw the launch of dozens of social networks, most long forgotten (remember Bolt.com? Don't worry. No one does). MySpace was the first one to really take the world by storm because its focus was on the profiles and direct interpersonal behavior. Social networks before MySpace had generally focused on creating group areas, games, and chat rooms. MySpace took what people had been doing on Geocities for years and systematized it.
But like all of the other social networks, MySpace got boring. It stayed the same, and I think that's why people ditched it. People have moved from network to network for the same reason that they change clothing. They like change. They might complain when it is forced upon them, but that constant updating is the only thing keeping them from jumping to an upstart competitor.
Analysts have been falling all over themselves in attempts at illuminating the drivers behind Facebook's rise and MySpace's fall, but I think that it's easy. It had absolutely nothing to do with the functional aspects of the service, it was entirely in the personality of the service. MySpace was glittery chaos, while on Facebook, no matter how trashy or horrible a person is, their profile is neat, trim, and organized. The whole service feels more professional.
But Facebook, I think, was a transitional service from the chaos of Geocities and MySpace to something more refined. Now that that role has been fulfilled, Facebook is in very dangerous territory. Facebook is explicitly aware of this situation, though, which is something MySpace certainly was not. Their frequent updates, strict image control, and constant refining of the user experience keeps them safe. Their personality remains refined, youthful, high-tech, and integral to a web-based life.