Dang, A-Cap brings the HEAT.
I'm checking it out. It's slick. I think I'll be trying it out for a few days, and then returning to Firefox. But I think Google expects people to do that. They don't actually want to have their own browser. They just want browsers to be faster, less crashy, and more secure. They have definite ideas about how to do that, and they wanted to release a proof of concept.
In the little comic they released, they basically came out and said, "We made our browser open source so other browsers would steal our ideas. If IE and Firefox would do things this way (i.e. 1 operating system process per tab, etc.), we could write mega-complex apps that make Google Maps look like a baby's toy. If we tried that today, we'd slow browsers to a crawl. So everybody make your browsers more like this one so we can make cooler gadgets for them."