According to Sony Worldwide Studios president Shuhei Yoshida, the PS4 won't have a power brick. Sony said they were able to build the console without anything on the outside.
Here's the official tweet from Yoshida:
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
The PlayStation 4 will be released Q4 2013.