Beneath the SurfaceIE9 will be able to tap into the GPU on Windows 7 and Windows Vista machines in order to balance the processing between GPU and CPU, making web graphics run faster. While Google admits their browser is still in the process of adding this feature (coming in Chrome 7), Mozilla says that Firefox had test builds that accelerated compositing and rendering "well before Microsoft". Browser hardware acceleration will exist in both IE9 Beta 1 and Firefox 4 Beta 5 as of today. Firefox additionally has hardware acceleration on Windows XP.
On the SurfaceMost of the new features in the first beta are interface and user experience changes. The screenshot below shows that tabs will be placed to the right and inline with the address bar in order to save space. Microsoft is also hoping to impress users with it's new smartphone-like approach, which allows users to pin website shortcuts onto the taskbar, similar to the mobile "apps" that take you directly to a web website or web application.
To some this may seem like just another area to put bookmarks, but this feature comes with some extra utility. Each website that is pinned to the taskbar has different 'tasks' (a subset of navigations) to enact within that website.
This feature also treats web apps more like the native apps that they resemble more and more. Microsoft says their new browser is 'site-centric, not browser-centric'. They say that the website has been promoted to a first-class citizen.