Well, if some big thing like this passes you by so closely, it's not difficult to understand how it can really end up haunting you. Especially if there was a lot of money and treachery involved.

Most developers (me included) know from personal experience how awful it is to watch someone you consider to be an asshole or a rip-off become very successful. Most of us also know how it the feels to discover that some company recently took off like a rocket with one of your ideas; usually they got the same idea independently, but if they actually copied it from you - that's a very special kind of pain.

That being said, I think it's important to remember the huge success of Facebook is not just based on the initial idea. There were many social networks before Facebook. As painful as it may be to some, the most important thing Facebook did was taking the company from the initial idea to where it is now and from where I stand neither the Winklevosses nor Aaron can really claim they did that.

As a developer and an ideas man myself, this is kind of a hard reality to face as well, because it means that in the end business practices and marketing are exponentially more important than concepts and programming.