For a long time, Google did not add new banner sizes to their AdSense inventory but it seems like that has changed. A few months ago, AdSense added a new 300×600 banner size and now they have gone ahead with and introduced a new 970×90 Super Leaderboard ad format which they claim is ‘brand friendly’.
970×90 ad units are an IAB standard so expect to see a lot of new advertisements targeting these sizes. Just like other AdSense units, these will work fine with both text and image ads. Google claims that these ad units will enable advertisers to promote their products on wide screens although it is yet to be seen how many publishers can adapt this size in their website designs. Having tested 300×600, I did not see any noticeable improvement to revenues compared to the standard MPU (300×250) or large MPU (336×280) ad units.
Google has highlighted the fact that since it is a new ad unit, publishers should expect to see either only text ads (up to 4 ads at a time) or 728×90 ( standard leaderboard ) display ads. Once the inventory for these ads starts growing, native 970×90 display ads should start appearing for publishers.
I am not sure if I would be able to give this ad unit size a go until I hear good things about it. It is already appearing on AdSense for me when creating new ad units. If you give it a try, let us know how your experience goes.