Chrome 18: Canvas2D GPU-acceleration + WebGL SwiftShader
The latest stable release of Google Chrome, Chrome 18 includes some change that should make HTML5 Game Developers happy. It enabled GPU-acceleration on Canvas2D on supported Windows and Mac computers.
On the WebGL side of things, Google has included a software shader called SwiftShader which means that the WebGL 3D canvas will be even available on older machines without supported hardware (albeit at a significant performance penalty).
Read the Chromium blog post for more details