It's not HD Graphics 4000. It's just HD Graphics, with no numbering. It only has 6 execution units (compared to 16 on HD 4000) and is clocked much lower.
Actually, per the datasheet[1] it has 4 EUs. I could not find any information about clocking the core, but I didn't search the entire 5100(!) page document.
I can see this being big with the media-art crowd for installations if it has any sort of real graphics oomph. From what I've heard the pi is just barely capable of hd video, anyone able to divine these tech specs into a comparison with the pi's graphics capability?