I just found a great research study on effective internal use of micro-blogging to enhance collaboration in a distributed engineering environment ... or should I say it found me via Twitter (thanks to Carrie Young). One of my favorite quotes from the executive summary: "93% of the answers were from a different NASA center". Explained in my own words, the NASA pilot participants received answers to their technical questions from fellow employees who they often did not know ... and who did not work at their own location. If you focus upon collaboration inside the firewall, and are exploring the use of Web 2.0 tools for the enterprise, this is must read. After all ... you have an elite university (CalTech) reviewing a complex distributed engineering environment (NASA). NASA's pilot project used Social Cast, but I found the findings to be software tool agnostic.
You may also wish to see my prior post on Collaboration in the Cloud.