Earlier quoted context omitted.
The GPU in a desktop is the only interesting kind of GPU. The built-in GPU in servers is ten years behind the current cutting edge on desktops. Though servers can have PCI Express slots for modern GPU installation. I think most of the GPU-based bitcoin farmers are using desktop hardware, but I might be wrong.
The built-in GPU on Xeons/Opterons/similar hardware is closer than you think. Not everybody needs Quattro/FirePro performance but a lot of people still want workstation/CAD graphics support in the drivers.
Xeon and Opteron CPUs generally don't have integrated GPUs. In fact, the primary difference between Intel's desktop and server LGA1155 CPUs is that most of the server equivalents have the GPU disabled (probably to save power).