We selected by:

1) Teams currently using an open source wiki tool. (Know the process & value; remove rouge software from company)

2) Teams that publish to large, but contained to a single department, email lists. (Process in place for writing frequent, quality content; focus is giving the readers a small, safe read-only introduction to community)

3) Teams with heavy document collaboration needs -- especially if team was globally dispersed. (Development)

4) Teams with a strong, passionate, voluteer leaders.

Our pilot membership was determined through the following highly scientific process:

1) Ask people we had to include

2) Ask people we wanted to include

3) People that found us.

This turned out to pretty much break out in the following manner

1) IT, Legal, HR, Communications

2) Anyone with a penchant for bucking the system, starting self-initiated IT projects, or possessing the unique mix of charisma and vision for open collaboration. This last group also had to prove it, not just say it. As in if they didn't actively participate, they were marginalized.

3) Other rogues hoping for a change.

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For us, it worked to keep the pilot "underground". Once we had our core folks lined up, we didn't turn anyone away and provided no direction on who to invite. We had no messaging, no marketing, no official backing. The viral approach took longer but eventually with 1/4 of the company still in the underground pilot, deploying "officially" was much easier.