Is coffee (ground, not instant) good for you?http://www.optimumnutrition4sport.com/?page_id=425
More generally on nutrition, some thought provoking views on the paleo diet have been challenging the established wisdom around how much of your diet should be carbs. (Google paleo diet or listen to Prof Tim Noakes on a recent episode of marathontalk.)
On a related theme, there's an interesting interview with the sports nutritionist Barry Murray (he's behind the website with the coffee article above ) on epidsode 19 of the podcast Talk Ultra http://www.marathontalk.com/archive/talk_ultra.php
which talks about adapting our bodiues to burn more fat and rely less on carbs.