No firm date has been set for either, but currently they are stating that they are both setting to launch for the Holiday season in 2013. Codename of XB3 is "Durango". PS4 Codename is "Orbis".
Both consoles are going to have Blu-Ray, with support for Single-Layer and Dual-layer, and higher-fidelity versions of their current motion control systems.
The X-Box 3 is going to have an 8-core 64-bit processor (assumedly an i7 or similar design) rated at 1.2 Teraflops. The PS4 will feature a 4-core 32-bit processor. XB3 will be using a GPU running support for DirectX 11, while the PS4 will be using an OpenGL 4 GPU. XB3 is specified to use 4 GB RAM, and the PS4 will be shipped with 2GB.
Specifications state that the PS4 will have *NO* hard drive by default, while the XB3 will come with a 500GB Hard Drive with 8GB of Flash memory. The XB3 will also have a 24/7 connectivity system which has not been entirely elaborated on, with coming support for cloud-based connectivity in 2015/2016.