More detailed specs

At the premiere event, Sony gave vague details about the "supercharged PC" architecture used in the PS4. It released more detailed specs shortly after.

Main Processor
Single-chip custom processor
CPU: x86-64 AMD “Jaguar,” 8 cores
GPU: 1.84 TFLOPS, AMD next-generation Radeon-based graphics engine

Memory
GDDR5, 8GB

Hard Disk
Built-in (no size specified)

Optical Drive (read only)
BD 6xCAV
DVD 8xCAV

I/O
Super-Speed USB (USB 3.0), AUX

Communication
Ethernet (10BASE-T, 100BASE-TX, 1000BASE-T)
IEEE 802.11b/g/n Wi-Fi
Bluetooth 2.1 (EDR)

AV Output
HDMI
Analog-AV out
Digital output (optical)

Third-party publishers

Sony released a PDF of third party publishers who are officially supporting the PlayStation 4. Unsurprisingly, it's a who's who of popular game publishers. Note that this is a list of publishers, not developers. Valve games have traditionally come to consoles published by Electronic Arts, and many of the games from Epic Games are published by other companies, for example.

4K is supported, but not for games

Thinking of buying a 4K TV in the next few years? Polygon confirmed that the PS4 will support 4K resolution for personal content like photos, but games will not run at that crazy resolution. That's probably for the best, considering that pushing all those pixels will likely have a severe impact on frame rates. Who knows what future system software updates will bring.

Sleep mode

Much like a modern smartphone, the PS4 will be designed to go to sleep rather than turn off. In this very, very low-power mode, the system is in a suspended state, and can wake up in just a second or two. It will even suspend the game you're playing and let you resume right where you stopped, Sony says.

This is a drastic improvement over today's state of affairs—turning on the system, waiting for it to boot, starting the game, waiting for the title screen, loading your save... it can take 3 to 5 minutes to get back to the game you were playing yesterday. With PS4, as with tablets and smartphones, that can take 3 to 5 seconds. This is in part thanks to the low-power sleep states of the modern PC processors and graphics chips used in the PS4, and I suspect the next Xbox to have similar capabilities.