Internet Explorer 8 Beta 1 is very near the launch and will be available for the general public to download and test. IE8 Beta 1 is focused on the developer community, with the goal of gaining valuable feedback to improve Internet Explorer 8 during the development process. According to Microsoft

We have identified you as a qualified beta tester and we would like to offer an opportunity to join our limited technical beta program for Windows Internet Explorer 8 Beta 1.

Participation in the Technical Beta will enable you to evaluate a common release of Windows Internet Explorer 8, the ability to submit feedback, post bug reports, download software answer surveys on product quality as well as vote on top bugs filed by others from the technical beta program. This is a very exclusive program, by invitation only. The only way to submit feedback is to enroll in the Windows Internet Explorer 8 Technical Beta program. As such, we would be happy to have your participation.

To accept this invitation and to apply to become a member of this program, follow this link

Follow the steps shown to you by that program to apply to become an active participant. You may be asked to take a survey, or submit other preliminary information. To report a problem or to ask a question, visit the Contact Us page (found at the bottom of every page).

Source: Microsoft