Good news! Chrome 13 was released today, and if you go to about:flags and enable "GPU accelerated canvas 2D", Chrome gets a nice solid 60fps on most games. Before, turning on the same option didn't seem to affect the framerate - seems they've done a lot better now.
You still have to manually enable it, but I think they'll enable by default in a release soon. Then, the big three - IE, Firefox and Chrome - all will have really good, fast, hardware accelerated canvases!