Internet Explorer 10 Release Preview for Windows 7 out now
Internet Explorer 10 Release Preview - Microsoft Windows
What those old fogeys among us used to call a "beta", before Google destroyed the meaning of that word so that everyone thought 'beta' meant 'fine to use'.
Anyway, if you want to try it out, it's available. Decent HTML5 support at last, though probably already obsoleted by Chrome as Google rush to implement more not-yet-ratified standards in order to stay ahead. The only visual clue to it being IE10 instead of IE9 is that the scroll bars look like Windows 8 ones.
No release date for final yet. Windows 8 has it already, obviously, but if you've rolled that out site-wide, you're a braver geek than I.