And plant switchgrass there? Seriously, people talk about the contribution of biofuels to high food prices, but we're forgetting that in some areas, vast swaths of farmland have been sold to developers and turned into exurbs. In the short time I lived in Idaho's Treasure Valley area, it seemed like the subdivisions doubled.

Now the housing bubble is popped, people don't want to spend gas money on the long commute and some of those houses are foreclosed and empty. Reversing the process of suburban sprawl would be incredibly difficult, if not downright impossible. But maybe it's time to start having a conversation about it.