From the Rex Kickstarter:

Why do you want Rex?

There are two general classes of electronics used in robot hardware: microcontrollers (ex. Arduino) and single-board computers. Microcontrollers are great for projects that only require a single program to be run, quickly and without overhead, like controlling LEDs and motors. Single-board computers are great for anything you'd need a cheap, small computer for - like networking applications and image processing.

Advanced autonomous robots require the strengths of both. A system developed around Rex, being made specifically for robots, brings it all together in one nice little package in a way that has never been done before.

Hardware Specs:

• Texas Instruments DM3730
• 1GHz 32-bit ARM Cortex-A8 Processor core
• 800MHz DSP core
• 512MB LPDDR RAM
• USB Host port
• MicroSD slot
• Camera Module port
• 3.5mm Audio-in jack
• 3.5mm Audio-out jack
• 5V DC input for desktop development

Each Rex will come pre-installed with Alphalem OS, a FOSS custom linux distribution. It includes a core set of built-in device drivers - ones that we've hand-picked as being the most useful for robots (like USB WiFi adapters and cameras). We'll publish the list in a wiki on our website.

Here are the other main features:

• An Arduino-style programming environment with support for multiple programming languages (C, C++, Python).
• A special task manager called the Master Control Program (MCP).
• An API for message passing in multi-process applications.
• A standard Linux filesystem which will allow you to install just about any Linux software that can be cross-compiled for ARM.
• Libraries for common processes such as I2C communication, face detection, and sensor reading.