Here are the clickthrough rates for regular Google search engine results page, according to the 2006 eye-tracking study (PDF) done by Cornell University:
Google SEPR Click and Attention distribution ‘heat-map’ (via seoresearcher.com)
Now, having blended results added to the equation should change the math. I would imagine the clickthrough rates going down as the attention shifts from top-left corner to the clearly visible video, local and news results. I would love to see a heatmap of the Google Universal Search results page.
So will the new blended results become the holy grail of search engine marketing? What do you think?