Don't know what this is referencing? Read this news item.

What I find particularly amusing as a non-Windows user is this excerpt:
The ads will appear during Skype-to-Skype audio calls for users of the Skype for Windows client.
Personally, the first time I see an ad in Skype is going to be the last time I use it. How is that a viable product direction for Skype to go in, seriously?