Originally Posted by xaira
these cards i believe are optimised for open gl and other professional standards, so even though its the same hardware, this will crush your 5870 in professional apps by miles
Well by a significant margin.
Most of the cost goes into driver development specifically for OpenGL, plus as professional application specific certification, such as Autodesk products, CAD/CAM (such as Solid Works) and special effects processing, real time imaging, etc. etc. etc.
Back in the X800 days, there was a hardware hack to take a $250 card and turn it into a $1500 FireGL workstation card. I'm not sure if that's even close to possible with the 58xx series.