Microsoft, always ready to introduce their own program naming, have introduced the concept of the “Platform Preview” for Internet Explorer 7, which you can download and try.
Basically, it’s IE but without the ability to change the URL or move backwards through pages – they want you to try it out, but without thinking this is anything like the end product. It can installed alongside your current IE version, however.
A Beta version of the full browser was available a while ago, though, but it was soon replaced with further Platform Previews.
One thing that IE9 does add is the ability for sites to create their own jump lists in Windows 7. Here’s an excellent article on how to achieve this. Google Chrome already supports jump lists, and it looks like Firefox will have it after 3.7 is released.