I'm one of the developers of threaded HTML parsing in WebKit. Threaded HTML parsing is only enabled in Chromium (for now). We're still working through the kinks. :)

Oh? So the "Last week in WebKit" isn't actually in the nightlies yet? Interesting.

It'd be better to think of it as "Last week in the WebKit project". As as the post points out, the WebKit nightly is only representative of the mac port of WebKit, which Apple mostly calls the shots on. In many cases Apple takes a conservative approach when enabling features that other ports may be implementing or experimenting with.

Peter's posts talk about everything that's going on in the WebKit project. The nightlies are just builds of Apple's Mac OS X and Windows ports.

Shadow DOM is also turned on for Webkit nightly. This article makes Chrome sound so much more advanced when in reality Webkit is only a couple of weeks behind.

I also have never seen people using -khtml- and -apple- prefixes.

I've only dabbled with the Shadow DOM, so maybe I'm missing something, but I just tried it in a webkit nightly and it did not seem accessible. The link in the article seems pretty convincing, though I can't conclusively judge from that that it's not enabled yet.

Also, the "also" in "also turned on" seems a little bit out of place considering the sibling comment to yours.