Link to an article explaining how they aren't really part of windows 8 but merely an "experiment". Fact is, install windows 8 and some of your apps will show ads (and when we saw them we had no idea that these apps were part of some "experiment" and not really windows 8).
Ah, so some apps that replace the Internet shortcuts that used to be installed with Windows have ads, just like the websites they're replacing. MSN showed a hell of a lot of ads, too.
Honestly, with a million little papercuts people are hell-bent on hating everything that comes from Microsoft. If you manufacture your outrage just right, it almost sounds legitimate.