IE9 has done a good job with Hardware acceleration but then its only developing for the one platform,
Heres a quote from the Opera Core Blog
http://my.opera.com/core/blog/2011/02/28/webgl-and-hardware-acceleration-2
“Our hardware acceleration is a bit different from what other browsers have implemented. Most of them do full hardware acceleration of all draw operations, but only on Windows Vista and Windows 7 – dropping to a more limited set of accelerated draw operations on other platforms. Our implementation will feature full acceleration on any OS with sufficient hardware support. This means we can also use fully hardware accelerated draw operations on Windows XP, Linux, Mac OS X and OpenGL ES 2 capable devices such as recent smart-phones and web-enabled TVs.
OpenGL
This build only has an OpenGL backend. That means your system must have an OpenGL 2.x compatible graphics card and related drivers for hardware acceleration and WebGL to work. In future builds we will also add a Direct3D backend, which will reduce the requirements on drivers and should work out of the box on most modern systems.”
That was published in February 2011 theres a link where you can download Opera with the Open GL drivers & have a 1,000 fish zipping around at 60fps on the fishtank demo if your graphics card supports OpenGL.