up down up down up down up down.
prices will rise, and then fall because they are unsustainable, and then they'll rise again, and fall again, and so on.
i think it will be a while before, at least in the U.S., we see a permanent rise in gas prices (i.e. >$5 gallon).
personally, it seems like somewhere between $3-4/gallon is a stable sweet spot, where it's expensive enough to encourage people to be more efficient without hugely damaging every sector of the economy (because everything gets transported one way or another)