I'm willing to talk to you! You can judge for yourself whether we meet your criteria for "successful," but I'm certainly pleased with the progress we have made in about 9 months. You can get an idea what we have been doing by reading our blog: Adventures in Social Media.
Send me a friend request in here if my email's not visible (I'm not sure if it is or not).
For your question about "who at Jive actually has done internal communication professionally with a focus on 2.0 tools?" - we all use SBS for almost everything we do at Jive, from planning software releases, defining company policy, tracking projects, etc.
We actually don't have an official community manager for our internal instance at Jive, although there are several Jivers who have taken various levels of self-management roles (reminding others of best practices as needed from time to time), and with our size company that's worked fairly well... though there's always room for improvement.
You'll find quite a few people here on Clearstep who are seeing great results with their internal communities, and who are very willing to discuss ideas. Probably best to just keep pushing out your questions or connecting with those who have already shared of their successes in various discussions on this site