An Ad hominem attack is a logical fallacy. If I say, "Scoble is an idiot", I'm not presenting an Ad Hominem attack. If I say , "Scoble is an idiot, therefore he is wrong about this thing" and don't present any counter evidence, I'm presenting an Ad Hominem
Saying, "Of course Rory would defend Microsoft, he works there" or "Scoble is just poting sour grapes because he doesn't work for Microsoft anymore" are also examples of Ad Hominem arguments.
Remember kids, insults are not Ad hominem.
Next time, we'll tackle the Strawman.
That being said, this kind of post by robert DOES fall into the "Scoble formula", if there is such a thing. Make a post based on inside information but make sure the post contains none of the inside information and just serves to essentially say "nyah, nyah.
I know something you don't know and I'm not tell-ing!" And it was old even back in the Longhorn hyping days on his blog.