From Wired:

Even if Bush’s hydrogen-car initiative is a cynical ploy, even if the Big Three are hiding behind hydrogen promises to prolong the reign of the V-8 and oilmen secretly want to strangle the fuel cell in its cradle, simple geology is carrying us toward a post-gasoline future. Petroleum’s days are numbered. GM executives themselves understand that. Some say the oil will last 20 more years and some say 50, but nobody says forever.

Wired: GM’s Billion-Dollar Bet