Sony has confirmed that the PlayStation 4 will come equipped with a 500 GB hard drive straight out of the box. Given the ever increasing size of downloadable games though, the hard drive is easily user replaceable and will support any size the owner might want.
The PlayStation 3 has a similar feature. I just finally upgraded from my old 60 GB hard drive to a nice 750 GB, and I feel like I have so much freedom.
By comparison, the Xbox One also comes with a 500 GB hard drive, but it is not replaceable. Owners wanting to expand the system’s memory storage will have to resort to USB devices and external hard drives.