Who's going to buy the ads?

The Day When Microsoft Pays You To Use Their Software: "An opinion piece over at Silicon.com is joking about how Bill Gates should be paying people to use Windows in response to a Bill Gates comment that Google should be paying people to use its search engine....Meanwhile, with Microsoft's recent announcement that they're focusing on software as a service, they did clearly say that they expect much of it to be ad supported. While many people question whether or not they can actually pull that off, if they can, how hard is it to leap from ad-supported software to 'make money' supported software?"

If everything is ad supported, who's going to buy the ads? It sounds like a bubble to me.