If you are that way inclined to test new applications then Microsoft do have Internet Explorer 10 available as a Platform Preview, not these previews are NOT full beta or Release Candidate (RC) versions, they are basic versions that have the core of the application as it may end up in a beta or RC version.
I have this preview running above in Windows 7.
All it does it give you a taster of how the browser may run on your PC, it has no main GUI menus as Internet Explorer 8 or 9 has, if you want to open a specific URL you will need to type or copy and paste it into the Page > Open dialogue box. Give it a whirl as it will run side by side with your normal browser so doesn’t remove IE8 or 9.
As reported by a few technology websites and blogs this week, IE10 will not be Vista compatible but will be only Windows 7 and more so Windows.next (aka Windows8 ) compatible.