I've been doing some more reading and, using the US as a model, I've seen the same thing crop (no pun intended) up time and again. Even if all the land capable of being used for growing was utilised for E85 production then it would still only produce about 10% of the US yearly fuel requirements! Now, headline attention grabber or not, it does seem to be born out by scientific types with their calculators.
Pretty much rules it out as a viable fuel in my opinion. The same goes for all other green alternatives. I've not yet read of anything truly green or sustainable. The best we can hope for is the tech guys get to grips with nuclear fusion.