The thing about Opera is, it only has around 2.5% of the market. IE9 will probably have over 30% of the browser market within two years, which is a major factor when thinking about any web development, especially with HTML5 features like canvas.
The reason it took longer for chrome is that they are trying to sandbox everything, including what goes through the GPU which according to the chrome devs is very difficult and painful. They could have gotten the whole thing to render on the GPU a long time ago if it wasn't for the sandboxing.
http://my.opera.com/core/blog/2009/02/04/vega
The interesting parts of the article are the implementation details about the sandbox.