The article above is an amazing article for all web designers. It's the first time I've seen the ability to actually use alpha layer of a png file, to have the transparent background actually remain transparent in the browser. It apparently works in both Internet Explorer and Firefox. The possibilities are endless with something like this, and it will definitely make things easier. Hopefully they keep pushing to get more and easier support.
I haven't exactly read the entire article so I can verify how easy or realistic it will be to implement it, but we're finally getting there 🙂