Internet Explorer 6 - is it irrelevent?

[serpicolugnut]

There are a number of sites/products that I see in the corporate environment which specifically disallow any browsers except IE.

Yes, this is due to User Agent checking most of the time (sometimes, it checks to see if ActiveX components are allowed, but that's just for sites that requires IE for Windows only). User Agent spoofing is quite effective on browsers that support it (both Camino and Safari both support it via modifying their prefs file or using the debug menu in Safari. iCab and OmniWeb have spoofing built-in to the program).

User Agent checks were necessary back in the days of IE 5 and NN4.7. Navigator 4.7 was so behind in standards support, that checking for IE was a necessity. Now that Mozilla, Netscape, Phoenix and Camino all use the uber standards compliant Gecko rendering engine, User Agent checks are less relevant.

Still, you do find many corp sites that still make use of them. 99% of the time, spoofing will trick the site in to thinking you are using IE though....