I think we're putting too much weight into this rumor. It is a blog post, which could have any realm of truth to it (so, it could be right on the money, or it could be totally wrong).
All features may have been implemented, but many are probably still in alpha form. To a degree, I'm talking out of my arse, because I don't have a copy of x86 OSX, but from what we have been hearing from the grapevine, a lot of stuff has still been relatively buggy, and there was still a LOT of stuff still running PowerPC code on Rosetta.
My prediction: Apple will stick to their timetable, if only because the chips they want to use aren't coming out until the timetable that they cited already (Merom, Conroe). I have my doubts about Yonah because it is not 64-bit... I think Apple will wait a couple months further for the 64-bit Merom, and let developers have a bit more time to boot.