What this means to us as professional web developers, is that all products (sites) must be 100% functional in Internet Explorer. There’s no room for excuses like “but it works in Firefox”. There can be no important features/styles/etc that only works in non-IE browsers.

I read about a lot of web developers saying “ignore IE and develop according to the standards”. Maybe that works for your own personal web site, viewed by 10 users a month. But if you’re running a professional site, supported by a large business, you can’t make it a crappy experience for all the regular users out there who aren’t using the latest Firefox or Safari build. That’s just dumb.
When the non-IE browsers have 95% of the market, we can start talking about ignoring IE and its quirks.

I’m not saying I like fixing IE bugs/quirks, but it’s a part of the job, just like any other task. Firefox (my own preference), Safari, Chrome or whatever are surely awesome browsers, far better than IE. But it doesn’t matter, because it’s only us “experts” and hardcore users that know about it. Your target group doesn’t.

So make it your primary goal to have the site working 100% in IE! If you want to use the extra goodies provided by other browsers, make that the little extra functionality that makes it a 110% experience in standards browsers.

(I do my primary development using FF and Firebug (as it’s much more efficient), and do a test round in IE 6+ when I’m done with the design. )