I'm currently beta testing new versions of Windows server, Microsoft Messenger, Windows installer, and (shortly) Windows Vista - it's enough, and I'm not looking for any more at the moment.
Beta testing - particularly in the early betas - requires a degree of commitment. You have to join special Microsoft Newsgroups and complete regular questionnaires - they nag you until you submit them. It can all be pretty time-consuming, and whenever there's a new Office or Windows beta coming along I tend to clear the decks for them.
Returning to your question - Chris Wilson's information is interesting,if he's right it sounds promising. I am pretty sure that Microsoft will open the throttle as far as IE development is concerned - they are intent on protecting their market share at all costs, and for good long-term reasons.