Clouding Computing Using GPUs

It seems that cloud computing and supercomputing have been in the conversion from massive CPUs to massive GPUs.
In the most recent Top500 Supercomputer list, although most supercomputers still use CPU and Linux, but one of them, the #5, uses ATI RadeonTM RV770 GPUs instead of x86 CPUs.
In a well-known blog post, How Will We Keep Supercomputing Super?, the author claims that due to the limitations stated by the Moore’s law, the complexity of CPU makes it costly (in frontend complexity and power consumption) to combine more of them to achieve better performance. On the contrast, it is more technologically reasonable to combine GPUs, which contains more and simpler cores than CPUs.
It is also noticeable that the biggest GPU producer, Nvidia, recently launched their cloud computing product, RealityServer, on Amazon’s cloud computing platform.