According to PC Watch, Sony are considering using a mainstream off-the-shelf processor for the PlayStation 4 as opposed to anything bespoke like the Cell. The processor for the PS4 will apparently be a multi-core affair, and one hopefully a lot easier for developerrs to get their heads around.
Other rumours coming out of Japan overnight include speculation that Sony also considered a combination Cell / Intel Larrabee duo, but have decided against it. PC Watch expect the PS4 to hit shelves in late 2012 or early 2013.