Ofocurse not, if you steal code from other programms then you cant open source "your own" peace of software, thats the only reason. I bet many parts of Ati closed driver are owned by someone else. If Ati release the code, they will be sued by several companies.Good question. We're only writing the closed source driver ourselves, and making use of existing closed source code in several places. We don't have any plans to make that code public in any form.
I can imagine that to clean up their driver will take many months and the driver will be slower so ati will never be able to beat the closed source driver of other companies e.g Nvidia.