Global warming itself is better discussed in the climate blogoshpere (check the climate sidebar), but geo-engineering seems to be an under-covered topic, which is unfortunate. Geo-engineering is an idea that has been around since at least the days of Edward Teller, who wanted to make harbors using thermonuclear detonations in Alaska. That was relatively small scale; move this piece of earth, here, and while the notion of using nukes to alter a small part of the earth's landscape is frightening, it is little compared to solutions designed for global warming.
Lowell Wood, a disciple of Edward Teller's, was featured prominently in an article in Rolling Stone, which stated out by describing him as Dr. Evil. Not Dr. Evil in the wacky "I'm a mad scientist teehee" sense, but Dr. Evil in the Dr. Strangelove sense; "I'm a mad scientist people take seriously, watch me say nuclear war is survivable teehee". Lowell Wood has a valid point in saying that all options should be considered. His opinion gets less merit when one looks at the ideas he tries to implement (with Edward Teller he worked on the Star Wars initiative), but when he says he has a cheap, temporary solution to global warming that will not require a lifestyle change, those in power could easily listen.
The solution being considered? Filling the atmosphere with particles to block out sunlight, in much the same way as volcanoes work. This will cool the earth for a bit, and then give us more time to develop a genuine solution to the problem. The particles will fall out of the atmosphere within a years time, and unless a solution has been developed, we can just shoot up more particles for the next year.
It's nutty, and it's out there, and while the potential to go wrong (the particles injected into the atmosphere are sulfur, which seems to be a direct trigger for acid rain) is huge, the idea is oddly fascinating. Not worth risking, of course, but certainly worth a look at.