Metrics around adoption of internal social computing technologies in the enterprise?

Ok - I feel that I'm missing something here - trying to get my hands around adoption rate (inside the firewall) of social computing technologies.

Only, what I find are:
1. External stuff - Forrester or Pew are sources for technical adoption profiles - externally - to my knowledge, this data is not available for enterprise users.
2. Internal stuff - adoption rates of "similar" technologies.

I don't think it is necessarily right to compare users in a professional services organization to all broadband users (though I think there would be similar breakdowns of collectors, producers, etc.).

At the same time, because there are so few social computing technologies inside the firewall to make comparisons - I mean, do I look at the adoption rates of Instant Messaging, for example?