IE was available for Mac until Safari came out. MS knows all about crushing the competition by bundling your browser with the OS, so they just skipped to the endgame and canceled IE.
IE9 isn't even available for Windows XP, I don't think need to say more. IE is a part of Windows, nothing more.
Microsoft Office is available for both Windows and OSX, why is iWork not available for Windows ?
Because Microsoft Office is a paid app and Microsoft want to squeeze some juice there as well I guess where as IE is free...and so...