Obama was against ending the current ban on offshore drilling, but now he's sort of open to it, if it's part of a bigger energy-independence deal. This has upset a number of his supporters who desperately want a president who will adhere firmly to his positions, even when they become totally irrational.
While McCain was never violently opposed to offshore drilling, he has now embraced it as if it is not only the solution to our energy problems, but also the key to eternal salvation. Really, it's a little scary. You can't help wondering if he's been captured by some kind of drilling cult.