Better CSS Page Layout.
This box model is a very easy and simple way to solve some usual problems in web design (form layout, page footers, vertical centering, disassociation of visual flow from HTML flow, etc.). I strongly suggest you become familiar with it because it could become a standard tool for web designers in the near future (if Microsoft decides to include it in IE, it could become so very fast).
— Mozilla Hacks, “The CSS 3 Flexible Box Model.”
I can’t wait until this is widely supported. Now that IE6 is dead (what, you’re still torturing yourself?), the current float / box model is the biggest hurdle to useful layouts.