Well.... I work for an IT consultancy firm and our job is usually to forecast technology leap. For fun at work, here's what a consultant predicted:
PS4 Specs:
Launch Date: July 2013
CPU: Cell Broadband Engine with 32 Cores (well, that really depends, he's thinking it's gonna be pretty cheap compared to the price of the current CBE when it came out)
RAM: 8 GB Graphics:
RSX GDR 2GB HDD: 4TB or 1TB SSD
OPTICAL Drive: Blu-ray (probably 400+ GB capactity)
VI: PS Eye 2.x
Controller: PS Wand / DS4
The actual launch price of the PS4 will be $399 - $499 depending on bundle and features. Both Version will include PS Eye and Controller. Surprisingly, if the PS4 does come out in 2013, the PS3 would phase out in 2015 in line with Sony 10 year plan. The PS3 is now over 3 years old.
On a side note, he claims that Natal will be huge but only with the X-Tri (His code name for the next Xbox - Which I think is catchy and MS will jump on)