Microsoft have released a preview version of the the new Internet Explorer 9. This will add better support for standards compliant css, and include paritial HTML 5 and CSS3 support.  Audio/Video tags will be a wecome addition for embedding rich media in pages. there is also GPU graphics acceleration which will increase the rendering time of web graphics. What is perhaps the most tempting change is the new Chakra javascript rendering engine which has been benchmarked using Sunspider as being faster than Firefox and only slightly behind Google Chrome, which has one of the fastest rendering engines of all major browsers. The graph below shows the relative results:

With the optimised javascript, it will be possible to use more client heavy webpages, paving the way for a new generation of cloud computing applications.

The biggest challenge MS will face when launching the new browser isn't features and performance, it will be security. With several recent high profile cases of browser hihack vulnerabilities, they will have to work hard to demonstrate that IE9 will be as secure, if not more secure than other established browsers.