Harold, good stuff. I would also suggest a fifth social network component, namely, "motivation promoters." As a former product marketing guy at a KM software provider, we saw that time and time again, without motivation (the carrot, not the stick) even the best initiatives become cloying to the folks in the trenches. We'll be seeing this as another key barrier to the success of any initiatives that rely on the latest renditions of social collaboration solutions in the enterprise. Hopefully, they are beating a path to your door.