Shuhei Yoshida confirmed the news via Twitter, putting an end to the speculation surrounding the system's power source. Lets just hope the PS4's heat output is less than the PS3's, that would be perfect in my book.
The power is inside, so no brick outside. “@ScottLowe: Get all cozy with the PlayStation 4: http://t.co/bf4l3Ad4pp”
— Shuhei Yoshida (@yosp) June 28, 2013