Thanks to Oscar Berg I found this article by IDG - saying "Collaboration Tools Worth the Investment, Survey Says" which is wonderful news. Not just becuase it's actually a good investment, but finally there are some numbers on this fuzzy term Enterprise 2.0.
The survey doesn't focus on any specific technology or feature such as wiki, instant messaging, etc - more collaboration tools in general - which results in that you can't really tell what delivered the most. I can't exactly agree on saying that VoIP falls under the umbrella collaboration, which was included in the survey.
However - pleasing to see that the business functions that had the most out of it was sales, marketing and R&D. The result is of-course faster development and more revenue - now we're talking money!
One interesting insight was that the users found the collaboration tools helping them balance work with their personal lives. I think it's interesting purely because it's a "non-figure-value" that they found and choose to highlight. In my opinion that is one of the huge benefits of working with collaboration tools such as wikis and blogs internally - it sets the spotlight on the individual - "you can make a change, your voice is heard and respected".
That individual satisfication - of being respected regardless of title on your business card - can't be measured in bills & coins.