After my blog was published yesterday I got a note from old friend Todd Ogasawara, editor of MobileAppsToday.com and MobileDevicesToday.com, who told me that Microsoft had a version of IE for Unix about a decade ago. Back then, Todd was designated a Microsoft MVP in that product area because of his work in trying to get IE to run on Solaris and HP-UX.
I did a bit of sleuthing, and Todd is absolutely right. Microsoft began development work on IE for Unix in 1996, and by 1998 had released versions of IE 4.0 for Unix on Solaris and on HP-UX. In 1999, Microsoft released IE 5 for both platforms.
However, that support didn't last particularly long. By 2002, Microsoft had abandoned IE for Unix. But the Web being what it is, you can find traces of its support. Surprisingly, there's still information on the Microsoft Web site about the platform -- here's a spec sheet detailing IE's Unix support. Here's the archived version for HP-UX, and here's the archived version for Solaris. And here's a screenshot of IE for Solaris from Wikipedia.
Why did Microsoft drop support for the platform? Most likely because the demand wasn't there, and was shrinking all the time. But the fact that it once had a Unix version shows that it's not averse to developing IE for other operating systems if it think that makes business sense.