Translated from this article:
Although both upcoming game consoles Xbox One and PlayStation 4 are based on AMD hardware, only PlayStation 4 incorporates hUMA [Heterogeneous Uniform Memory Access] for supporting a shared memory space. This was explained by AMD's Senior Product Marketing Manager Marc Diana to c't [big German IT magazine] at gamescom. This should put the 3D-performance of PlayStation 4 much farther ahead of Xbox One than many have expected so far. AMD sees hUMA as a key element for drastic performance improvements in combined processors. AMD's upcoming Kaveri desktop processors support hUMA as well.
Behind the scenes, c't could hear from developers that the 3D-performance of PlayStation 4 is very far ahead of Xbox One.
Back in April, AMD manager Phil Rogers explained to c't that hUMA improves 3D-performance in particular. "Game developers have been eager to use very large textures for years. Until now they had to resort to tricks in order to package parts of larger textures into smaller textures. That is because today a texture has to be located in a special place of physical memory before the GPU can process it. With hUMA, applications can work with textures much more efficiently". AMD will give more details on hUMA at its upcoming developer conference in November.
Surprising that AMD would come out and talk about something like this publicly, going to guess it was supposed to be off the record.
Also another article speaking to AMD planning to sell a cut down version of the PS4 APU for PCs. Sounds like a cost effective solution for budget gaming PCs down the line probably, which could be a boon for PC games. I wonder if something like this would show up in a Steambox down the line.