Pixel was completely misused in the article. He's working an image scaling algorithm for photos. That isn't saying that it's not noteworthy, interesting or important; it looks like it works great and I'm not aware of anything that produces results that good on photos. There is the Hqx family of filters, but those were designed for emulators and aren't meant to be used with more than 256 colors.

It is backwards compatible with DS and DSiWare games. That was said during the keynote but articles don't seem to mention it for some reason.

Do they mean it this time?

MNG is the "official" animated version. APNG was rejected as an official extension. However, APNG is backwards compatible with PNG, a static image is displayed instead of an animated one in browsers that don't support it, and it also supported by more browsers. Firefox 3+ and Opera 9.5+ support APNG, but only Konqueror currently supports MNG out of the box.

Plus, it runs on the most platforms; Windows, OS X, Linux, Solaris, FreeBSD, Symbian* and Windows Mobile*; and it's just vanilla HTML, JS and SVG zipped up.
*Once Opera Mobile 9.5 ships.