Weeeeeee-l-l, off-shore drilling is not as ecologically hazardous as its often made out to be. But accidents can be catastrophic, but they are rare, especially with American rigs.
What bothers me about this, primarily, is that its not really going to do much good . . by the time the new rigs are up and running we'll be out of the current crisis. I think we'd be better served by throwing our resources all out at renewable solutions (NOT corn bio-fuel). However, considering that is unlikely to happen, it will reduce our future dependance on foreign oil, which is a national security benefit. All in all, I'd rather they didn't do it . . .but it doesn't horrify me.
I do think this is a political manuver on Bush's part, rather than one really intended to be helpful.