You're going to see quite a few HM/QS 55 or 57 variations once Arrandale line roles out.
PM55 is for Clarksfiled since it lacks an onboard IGP solution. This tends to reflect Intel's past nomenclature for Premium or Graphic enabled chipsets.
H is a newcomer though.
Seriously, Eidorian, do you spend all your free time memorizing the names and specs of Intel chips and chipsets?
Anyway, what are the chances of a higher-end CPU (quad-core?) and dedicated graphics card in the next-gen 13" MBP? Or is Apple still too scared to go beyond integrated in the 13"? I still remember the 12" iBook (my parents have one), which had dedicated graphics. And Steve Jobs was making fun of Intel integrated graphics, and then promptly decided to put them into the 13" Macbook. The iBook had better graphics power than the Macbook for a while.
The problem is, these Macbooks are so thin and hot, I wonder if there are any chances of some power. Sure wuld be nice to stick with a Mac for my next notebook, rather than switching to a Windows-based 12-13-incher with some rea graphics and processor power. And that runs cooler.