Internet Explorer 7 for XP Released
Despite still being behind in overall CSS support compared to other browsers, I think this is a huge gain for us in the trenches. The quicker the rollout, the sooner we can leave a number of frustrations behind. Yes, there will still be continued frustration from bugs that haven't been fixed, bugs that have been introduced, and the lack of certain CSS support that we'd all love to see.
Min/Max-height/width is in, fixed positioning (yay, my fixed comments work in IE!), along with a bunch of handy selectors like first-child, adjacent and attribute selectors. These alone will help simplify a fair bit of styling that might have otherwise required extraneous class names littering our HTML.
Now that IE7 is out, we can all start talking about the imminent release of Firefox 2.