According to Forrester’s G. Oliver Young the global Enterprise 2.0 market will grow from 455 millions in 2007 to 4.3 billions in 2013. Well, even 0.5 billions in 2007 are quite a lot compared with a global ECM software spending of 1.5 billions.
Major points of this Forrester report have been discussed e.g. by ZDNet blogger Larry Dignan. But I don’t think that

[...]For instance, social networking is a decent substitute for knowledge management applications, a category that companies haven’t quite cracked.[...]

I still see social networking as a supplement that adds value. Therefore, social networking should be part of the KM approach.
Oliver presents an abstract of his findings e.g. also in an article for the Indian Express Computer magazine. The interesting point is at the end of the article where Oliver points to the assumption that

[...]Forrester expects far greater demand for process engineering and change management services than for systems integration because many of the early adopters have reported much more difficultly with cultural change and adoption than with technology integration and optimization.[...]