The new browser, Chrome, is clearly marked as a developer preview, and not meant for general browsing. In fact, as a good Mac citizen, it will refuse to set itself as your default browser.
It scores a 100 on the Acid3 test straight out of the box, but doesn't pass: it fails something called the linktest, which involves interacting A tags and IFRAMEs. A little research suggests that it could be a bug with Webkit. If that's true, then it's a bug that Safari 4 beta has fixed.
Again, Google Chrome isn't for everyone, but if you're a web developer who needs to keep up with the bleeding edge of browser development, then this preview should be stable and reliable enough for you to test what you need to.
Thanks to everyone who sent this in!
Update: Commenter Manu points out that there are other, possibly better, tests out there that give different results. Thanks, Manu!