It looks like some clever users have already extracted the new Windows 7 icons, so users of XP and Vista can them if desired 
A big icon pack with over 500 Windows 7 icons can be found here:
http://nhatpg.deviantart.com/art/Big-Windows-7-s-icons-pack-111383821
A big icon pack with over 500 Windows 7 icons can be found here:
http://nhatpg.deviantart.com/art/Big-Windows-7-s-icons-pack-111383821