netmeg - 12:28 pm on Aug 7, 2012 (gmt 0)
I doubt it will ever happen. It would be abused even worse than it's abused now. And we all know that giving publishers more control over the product is not a high priority with Google.
Most of the sizes we have are industry standard (IAB) sizes for ads.
Not being a premium publisher, I don't know if they get to define their own ad sizes, or they just have more to choose from.