PS4 dev kit was at 1.25Tflops (GPUs), and the 720 dev kit was at 1.4 TFlops (GPU). These first dev kits are 6 times more powerful then the current hardware.
I think when these consoles are released they'll both sit around 2.5TFLOPS for total GPU power. Primarily because of statements made by Epic's Tim Sweeney, who stated that Samaritan Demo would require next gen consoles to have 2.5TFLOPS of graphics power to render the demo at 1080p. Epic had a big hand in the development of the 360, and this generation has seen Unreal Engine 3 become the go to engine of choice for developers, I'm sure Unreal Engine 4 will have a similar impact.
2.5TFLOPS is 10 times more powerful then what we have now, I can't wait to see what kind of things developers will do with that kind of power.
Rumors point to the next xbox have an 8 core CPU, while Sony would have 4. For Sony to add a second CPU would be extremly costly, and wouldn't be very power efficient. Don't forget that xbox 720 will not only have kinect 2, but also rumored body sensors, heads up display, and DVR functionality; these could easily chew up 2-4 cores. It's likely that the 720 will need the extra 4 cores just to stay even with the PS4.