Cisco have shared the strategy they've had developed for them by Frost and Sullivan in a piece called the Social Media Centre of Excellence. A nice chart showing the development process is here:
Meanwhile, Dion Hinchcliffe at DachisGroup writes a useful piece on social business transformation here. He includes a well-drawn chart illustrating the various phases of maturity for social enterprises.
Finally, eMarketer charts the big slow-down in growth for Facebook. Whilst they still dwarf Twitter massively, Twitter's growth rate shows a strong curve.