E4X in ActionScript 313 Oct 2005
E4X stands for ECMAScript for XML. XML would be native data type in future versions of ECMAScript. It was known to world accidently but recently support for this feature announced officially.
Brajeshwar has posted a nice intro article on the E4X.
BTW! If you are wondering, how can you start playing with it until Macromedia Flash Player 8.5 is out. I think, you can use FireFox 1.1 or above for that. E4X support is by default on in FireFox 1.5 or above.
Some more links on E4X: