Seems Kotaku has acquired some info on the supposed PS4, from the same guy who was trying to sell that Xbox Dev Kit on eBay a few months ago.
Link
The following specs are for the units currently at developers so stuff may obvioulsy change for retail release.
Specs:
System Memory: 8GB Video Memory: 2.2 GB CPU: 4x Dual-Core AMD64 "Bulldozer" (so, 8x cores) GPU: AMD R10xx Ports: 4x USB 3.0, 2x Ethernet Drive: Blu-Ray HDD: 160GB Audio Output: HDMI & Optical, 2.0, 5.1 & 7.1 channels
The new controller might have a back touch pad like the Vita with multi-touch.
PSN accounts would be able to be linked to controllers, allowing for multiple logins on the one system so multiple people could earn trophies when playing co-op.