In the Brave New World that is Web 2.0, everyone's going to use their browser for everything. Word Processor? Google Documents, via your browser. Email? Gmail, via your browser. Remote login? Thin Client, via (you guessed it) your browser.
What made the buzz get cranked all the way up to 11 is that you don't need to care about what computer people use to connect. Use whatever you want. Windows? Sure. Linux? OK, geek boy. Mac? Get your Think Different cult on. Everyone plays!
So what happens when there's a security bug in the browser? Ah, but there are so many browsers. Firefox, Internet Explorer, Opera, Chrome. They can't all be bad, right?
Wrong. OK, technically, they're not vulnerable. But they run Quicktime, which is vulnerable, and which is all over Al Gore's Intarwebz. All browsers run Quicktime. And Quicktime has a nasty bug that will get you pwned, no matter who you are.
So clicky here to patch. Yes, you.