It seems that overlay is the way to go for TV ads - Google, as I've previously predicted, have now rolled out their overlay proposition on Flash videos, and Silverlight is not far behind in offering this capability on Windows Media clips. It's something that Joost pioneered and is set to become ubiquitous as a medium for internet tv - especially for short form content.

However, Google has struggled to make its ad engine work with display ads (there's no little or no data to parse), hence their buying Doubleclick, and I'm unsure if the overlays are graphic or textual, and how easy it would be to contextualise them.

But you can see Google's strategy beginning to come together - text ads, display ads, radio ads and video ads from the same company.