Microsoft just released a new Platform Preview build of Internet Explorer 9. (This is PP7, for those who are keeping track.) It’s available for download at the IE Test Drive site.
The Platform Previews are intended for developers to test performance and compatibility; they don’t have a user interface and aren’t suitable for day-to-day use. But the good news is you can install them alongside any other Internet Explorer version (including the IE9 beta) without conflict. I’ll be testing PP7 today and will have more to say about it later.
If you’re interested in testing one of these builds on Windows Vista or Windows 7 (the only two supported platforms), you might need to install some updates first. You can find the full list, with instructions and download links, here:
Required Update Installation Instructions
The Platform Preview builds require updates to be installed on both Windows Vista and Windows 7 systems. These updates support Platform Preview graphics, media, and printing functionality. The Platform Preview is designed to install the prerequisites automatically. However, if the Platform Preview encounters an error while installing the prerequisites, you can install them manually using the below instructions prior to installing the Platform Preview.
I assume (but haven’t yet confirmed) that these same updates will be required for the final version of IE9 and will probably also be in Windows 7 Service Pack 1.
Ed Bott (@ wordpress.com) 
Ed, have you discovered whether the same method of grafting the platform preview engine into the IE9 beta works as it did with the prior PP?
(I will try later and post results if I don’t find an answer here. That is the browser I’m running while typing this.)
Thanks.
It seems pretty clear they’re getting closer if they are dealing with print and the like.
OK, it appears that the same process for mashing the PP engine into the IE9 beta works with PP7 as did with PP6. Preliminary results only (but I get a seemingly-working browser out of it–which which once again I am typing). (Sorry, I’m hedging on the method–I built my PP7 one using PP6 as a model, and I can’t find a link.)
I hate to say it, but so far I’m extremely un-impressed by I.E. 9. The “minimalist” idea is extremely annoying. And it has wrecked my browsing experience. It’s sad when a new product moves you backwards more than forwards. Support for HTML 5 is great and all, but they just went way too far with 9.
Ed, when will IE 9 RTM be?
MH, there’s no official word yet, although Microsoft has said it will be in the first half of 2011 (and probably in Q1).
http://www.zdnet.com/blog/bott/cast-your-vote-in-the-ie9-release-date-prediction-pool/2301