There are now well over 500 registered members on the Open XML Developer community site, and from what I've heard there were over 20,000 unique visitors last month alone. I'm not sure if you guys have been out to the site lately, but there are a ton of great discussions going on in the forums, and the sample solutions being posted are really great.
The latest article up there covers how to View revisions to a WordprocessingML document in a browser. It shows how you can take advantage of the rich revision tracking support in a browser. There are also some great examples of how to program against the formats just using simple Java tools so you can use the solutions on any platform (Linux, Mac, Windows, etc.).
I've really enjoyed the ideas we've seen pop up over there, and now that the technical refresh of Beta 2 is out I think we'll see even more solutions coming along.