Well, this was the week that the world of web design was turned on its head. The release of Firefox 2.0 wasn't the cause: it's only Microsoft who can shake the industry up like this with it's release of Windows Internet Explorer 7.
It's been 5 years with the same IE bugs, but now we get a lot of them taken away and a whole new load handed back. Because of this, we once again have three major platforms to target: IE6, IE7 and Real Browsers. There has been a lot of talk about better standards compliance in IE7 but it only takes a glance at comparative Acid2 renderings to see that IE is still way off the mark. Firefox 2 doesn't pass Acid2, but its performance is actually not bad at all. In fact there is only one major class of bugs left for Acid2, bugs which will all be fixed by the reflow rewrite, which has been in progress for a while now.