Microsoft announced, not too long ago, about a pilot program which aims to put advertising into Zune Social. The blogosphere has responded with a resounding "NO!" at this news. However, most bloggers probably assumed the worst (pop-up advertisements while trying to navigate to the next song or something). So, ArsTechnica has a write up explaining what exactly Zune Ads is all about.
To begin with, the advertising is not just limited to the Zune. It is a move by Microsoft to offer ads on Xbox 360, Xbox Live, Windows Mobile, and Microsoft Surface would all be part of this system as well. Microsoft is testing a new frontier by also making the ads interactive and enjoyable and giving users the choice to view ads or not. At this point it seems that the advertising will only come along with free content, like an MP3, wallpapers, trailers, etc. which means that the advertising will be completely optional.