So, putting the movie aside, how was facebook able to go well beyond similar social networking sites that had even gone live before it? Before we can discuss this, we must first agree that facebook is more popular that any other social networking site.
In order to become popular, a site needs to go through the following - attract popular people (who will in turn attract other popular people), create a critical mass (so that membership can increase exponentially and quickly) and finally, continue to remain popular. I said "site", but this is true for most elements in society that thrive on popularity, be it the local restaurant or bar even.

So, the final step - continue to remain popular - this is without doubt the hardest thing to do. Every dog has its day, and the biggest of kingdoms have risen and fallen. So, how does facebook do it? Innovation! Facebook has continued to innovate and change to add new features and to remove stale features as online social culture changes. They continue to add new features like photos and tagging as well as games etc. while removing features (shall remain unnamed) that possibly weren't so popular. Remember, that in all this, money definitely helps! Popularity attracts talent and ultimately, you need to pay that talent. However, it just isn't about money, but the innovative ideas and continuing changes - the urge to not settle, but to continue to improve. I'm sure a lot of people are going to argue that the continuing changes make facebook unpopular and I will politely disagree. The "popular" crowd (or the early adopters), the crowd that actually attracts other people to some place (site / bar etc.) doesn't want to have the same thing forever. These people thrive on something new, which is why, different sites / bars / clubs etc. rise in popularity. Facebook does a great job at continuing to change and then helping to make the transition smooth for the later adopters. This is why I believe they continue to be popular and kudos to them.
Before I close, I ask you, what are your thoughts? Has facebook peaked? What of LinkedIn? Thoughts to be shared on another post, but would love to hear more of what you think.