Prediction: Facebook will be the largest social network in the world
paulallen.net
paulallen.net
Social Networks are still very young, Facebook is promising but the game isn't won yet.
However, the internet has several billion users, and 90% of them log on every day (I made those numbers up, but you get the idea). So where is the difference to Facebook? Just because somebody is using Facebook doesn't guarantee that they are using your Facebook plugin. And once there are as many plugins as there are services on the internet as a whole, I don't see an additional advantage for Facebook...
Just playing devils advocate, it just seems to me some people are being blinded by the dollar signs in their eyes. Sure, it would be nice to write a plugin that every facebook users uses, but in general it won't be so easy.
There is probably a bonus for being an early starter now, though.
I think the real win is that their api allows your app to take advantage of the connections between facebook's users.
Facebook will probably be hot until something an order of magnitude better comes along, and even then many people will not want to switch (inertia). Add to this the open approach (API + site integration), and it isn't too far a stretch to see them becoming the standard social operating system.