The short answer is, it depends. There are many ways to interpret Lean, just as there are many ways to interpret social business, and some of the tools used under these names are not compatible with each other. However, the thing I am most interested in is their compatibility on a very fundamental level, on the level of their core premises from which the various tools are but imperfect manifestations.
Just like value-stream mapping is not the same thing as Lean, crowdsourcing is not the same thing as social business. While a toolkit approach to Lean or social business may produce results, it is usually very difficult to retain those results unless the toolkit is based on something more and ingrained into the corporate culture. In order to explore the compatibility of the paradigms, it is necessary to explore their core.