Here's a quote from the anandtech review and why GP-GPU is getting so much attention
....Bottom of the page.
So long as you only want to handle the highly parallel workloads VLIW is fine. But using VLIW as the basis of a compute architecture is going is limit what tasks your processor is sufficiently good at. If you want to handle a wider spectrum of compute workloads you need a more general purpose architecture, and this is the situation AMD faced.
But why does AMD want to chase compute in the first place when they already have a successful graphics GPU business? In the long term GCN plays a big part in AMDís Fusion plans, but in the short term thereís a much simpler answer: because they have to.
In Q3í2011 NVIDIAís Professional Solutions Business (Quadro + Tesla) had an operating income of 95M on 230M in revenue. Their (consumer) GPU business had an operating income of 146M, but on a much larger 644M in revenue. Professional products have much higher profit margins and itís a growing business, particularly the GPU computing side. As it stands NVIDIA and AMD may have relatively equal shares of the discrete GPU market, but itís NVIDIA that makes all the money. For AMDís GPU business itís no longer enough to focus only on graphics, they need a larger piece of the professional product market to survive and thrive in the future. And thus we have GCN.
Basically gaming isn't enough anymore and AMD wants of piece of that compute market, wich is highly profitable, hence why the GCN shader architecture was developed and they didn't stick with VLIW as in previous AMD GPU's...