Visible bindings

Just noticed this: Two-Way Data Binding in Flex 4.

Flex is an SDK for building Flash apps that I know nothing about, but this article presents what looks like a rough equivalent of Cocoa Bindings, and it has one really nice property that Cocoa has always been missing - say what you want about specifying a UI with XML, but the Flex XML looked like it'd be relatively easy to scan, search and diff. I've always thought that a human-readable text format for Cocoa NIBs would be a big improvement.