Yes, excellent post Gav. This is an important area of study. Here in the 4th corner of the U.S. we have some folks working on terra preta as well.

To add to your "Further Reading" list, check out "Charcoal, Agriculture and Climate Change" by Richard Haard, PhD. at the Energy Bulletin.
http://www.energybulletin.net/node/46029

Thanks - I missed that article when it came out - its a good addition to the list.