If you want to download IE8 Beta 1 and test it, it's here. Read the Release notes and the IE8 Readiness Toolkit which will give a detailed description of the features.
If you have any feedback, use the feedback form, which allows you to submit bugs directly to the IE team!
Several updates have been made to the IE8: Technical Beta Program available on connect. Check it out!
Also check out the IE team's blog: