I really like this graph (found through NRO).Basically President Bush's poll numbers seem to follow the inverse of gas prices almost exactly. While the rights and wrongs of the war may be a difficult issue to gauge, gas at $3 a gallon is all bad.
In Britain they're paying around $6.40 for a gallon. (It's around $5 a gallon here). Bush would be impeached long before the price got anywhere near that level.