Let me ask everyone participating in this thread how much it matters when web designers have web sites that only rock on 5.x/6.x browsers, when the people mostly visiting a web designer's site are... web designers using the latest browser versions!
Now, there is one other kind of person visiting a web designer's site: potential clients. Um, let me rephrase that: potential clients probably using legacy browsers.
Potential clients that would stipulate that any site made for them work in all browsers.
Potential clients that don't know a <table> from a <div>, and, perception being reality, will think the reason why your site looks like garbage in their 4.x browser is because you suck!
Zeldman speaks for all of us in voicing our desire for standards compliance. Because of the public's lack of knowledge on the issue (and really, they shouldn't have to know), the vendors will continue to have us by the shorties.