If you don’t know what the getBoundingClientRect method is, you can read about it at the Mozilla Developer Center site or at the Microsoft Developer Network site — or better yet, read what John Resig has to say about it.

WebKit was the last remaining major browser engine that lacked support for getBoundingClientRect (and for the related getClientRects method) — until yesterday, when Sam Weinig landed support for it in WebKit too.

In my book at least, adding another useful supported-across-all-major-browsers feature to the open Web platform is a pretty cool thing. And as far as why this feature in particular is a worthwhile addition, well, you might want to go back on read John Resig’s write-up about it; title: getBoundingClientRect is Awesome.