This is an older piece from February 2001 over at A List Apart, but I think we'll see its message in practice even more since Netscape 7/Mozilla 1.0 now offer a better alternative to Netscape 4x (at least, on newer machines which can run it).

And I sympathize with the views of this piece. Trying to design for Netscape 4x and older browsers, which aren't even close to w3c compliant is a lot of extra work and testing.

Meanwhile, it's also already happening within my academic discipline. The Computers and Writing 2003 Conference abstract submission system is guaranteed to work only for new browsers.