Bing has confirmed that CTR is now a factor in its Ranking algorithm, Bing has confirmed this at the SMX east. This has been confirmed by Steve Tullis a senior manager at Bing. Google has stated that CTR is not a important factor in their ranking algorithm.
Another interesting development is that Firefox is now set its standard search provider to be Bing, this is a great move for Bing as many hundred million people use Fire Fox on a daily basis. This is why Google has moved its emphasis towards chrome.