Internet Explorer 8 preview:

http://www.microsoft.com/windows/products/winfamily/ie/ie8/default.mspx

Looks a bit like IE7 enhanced to me.

I suppose they need to keep up with FF and the like.

I wouldn't recommend installing the beta. Some people I know are trying it out on different OS's and they say it needs a lot more work before release. I don't even think you can do a roll back once it's installed to get your old settings back.

It's the same with most of these betas, you must completely uninstall before attempting to install the final build.

I just wait for Windows Update to give me the final build.