The Schema Course Extension community group was launched in December. It now has ~30 participants and Phil Barker was chosen as chair. More participants are welcome, In order to join the group, you will need a W3C account (but not full W3C Membership.
The best way to proceed was discussed in a conference call in January, notes from which are available. In that call it was suggested that discussion be structured around a list of what the extension should enable and examples based on data from real websites. These use case outlines and a short list of example sites from which data can be summarised are now on the group wiki. Hopefully we can knock most of them off one at time fairly quickly.