Ross Mayfield has recently published a brilliant article titled An Adoption Strategy for Social Software in the Enterprise. on Many-to-Many which describes a strategy for growing grass-roots adoption of social software.
Top-down instruction may seem more appropriate in some environments, but may not be effective in the long-term as if the team leader stops actively making subordinates use the software, they may naturally give up if they have not become convinced of its usefulness. Bottom-up adoption taps into social incentives for contribution and fosters a culture of working openly that has greater strategic benefits. Inevitably in a successful deployment, top-down and bottom-up align themselves in what Ross Mayfield calls ‘middlespace’.
Having witnessed so many software/communication projects grinding to a halt through poor uptake I think that this type of approach has a lot going for it. Too often all the energy is focused on the technology rather than the whole product.