Some optimism from a US administration figure that the increasing attractiveness of agro-based fuels will bring progress in Doha. Of course this over-simplifies the issue, and the catches are many. I could've posted this as a trade law "brain-teaser", but see this interesting discussion paper, co-authored by Rob Howse, discussing the whole slew of WTO disciplines that may be relevant to production of and trade in biofuels.
T.