I can't stress enough how important this is for all Safari users. Most developers still use Windows when developing web sites (it's changing, but don't try to fool me, we're not there yet). Will all these developers test in Safari? Hell no, even though there's probably some hacky way to get Safari running, but I doubt many will go through the hassle of doing it. I know I don't. I also know that I now will test in Safari. For starters, this site is broken, need to fix.
Congratulations all users of Safari, you have a bright future ahead of you. Also congratulations to Apple, for playing their cards exactly right (first Intel Macs, now this).