You mean so all the windows on my XP machine have a different look and the "minimize" buttons don't line up when I stack multiple windows on top of each other? No thanks.
At a glance, I thought that the article title meant that Firefox 4.0 was going to be based upon the Chrome browser, and therefore Webkit... no such luck, I guess. A browser which has full compatibility with the Firefox legacy of plug-ins, and runs on the Webkit rendering engine would almost certainly replace Safari as my default browser on both my Macintosh and my PC -- and I would hazard a guess that I'm not the only one who could say this. What's more, then the "browser wars" would effectively be whittled (back) down to a boxing match between Internet Explorer and Webkit, instead of this wild-and-crazy-free-for-all that's been going on ever since Netscape gave up the fight and sold out to AOL. Maybe then, the collective market share of all of these webkit-based browsers might drive web development more strongly to a "standards centered" philosophy of design and away from the "IE workaround" philosophy of design.
Ah, well. A guy can dream, can't he?
Make sure your code does nothing gracefully.