You are looking at it backwards. They are not adding a phone to a psp... they are adding a psp to a phone.
If you had two android phones to look at, and all else being equal, but one having the ability to download and play games from psn... would that make a difference?
To me, if the price difference isnt huge, it would sway my decision. As long as this has all the compatability/apps/and functionality of any other premium android phone. Although psp games might be annoying without the nub.
However, all other games that like to use those on screen touch dpad and buttons would be much better (phone games, such as zenonia.)
I'm interested to see this after release... may be a tossup between this and iphone4 in dec2011 when its contract renewal time.