As promised, I attended Marc Canter's BOF on microformats and structured blogging during MIX06. My questions were answered by Tantek Çelik, one of the people pushing microformats:

1. How do you get people to agree on the schemas? Derive them from current practice on the web rather then inventing them from scratch (paraphrased).
   
2. How do you handle the need for both a rich schema for "high end" applications and a simple schema for "low end" applications? Both will exist (paraphrased).

I like the answer to question one. The answer to question two may need some more work. Eron Wright's suggestion to use modularization and profiles makes sense.