At the Online Community Business Forum, Forum One’s Bill Johnson and Joe Cothrel of Litium Technologies offered a recap of CoP ROI statistics that are publicly available.
While most of them are evidently derived from success stories and are, as such, a mixed reference for people evaluating the prospect of a CoP (the effectiveness depends on the situation: not everyone profits equally from a CoP)… well, it’s evidently heavy artillery for the CoP’s cause. I wish I could get the links to the original documentation of those cases.
The slides are here (most interesting, too). I had a sense of dejà vu on page 4, but I don’t remember when I first saw that figure.