Snickersnack: Internet Explorer is an important browser that effects everyone on the web. As such, it's a valuable piece of software to run on Windows compatible platforms but you still need a MS Windows license (pricey) to run legally.
I would guess the list is aimed at Windows users anyway. Of course, those running Windows (95b or newer) already have some version of Internet Explorer. I'm still not sure what you're trying to say.
adambiser: I thought they had IE on Mac as well.
"Had" being the important bit there. It was discontinued in 2003 after version 5.2.3 and 5.1.7 (For OS X and Mac OS 9, respectively), which was in some ways much more advanced than Internet Explorer for Windows, at least until IE7 arrived (and worse in other ways), it also used different javascript and rendering engines from IE for Windows, so it wasn't the same application by most measures.
There were also Unix versions of Explorer 4 (for HP/UX, and a couple others), these, however, were ports of the Windows version, unlike the mac version.