There is now an ArcGIS 10.0 add-in available as a download from the Google Code site. It is available here.
This should enable ArcGIS 10.0 users to also easily browse and get data from GeoCommons. Sorry, I don’t have the add-in code available yet. I’m a little swamped so it’ll be a while before I get to that but I wanted to make the download available.