Why spending time in something that you cannot purchase to put in your product ?
This is vaporware.
Try Linux Stamp ( http://www.thelinuxstamp.com/ )
Use Atmel, you can purchase the chips right in the corner;
Datasheets ? Get full datasheets at atmel.com.
Let me try those links again. The parentheses created confusion.
RasPi is a terrific GNU/Linux platform for the price, with a strong developer community. However, GNU/Linux is in many ways a mainframe operating system and programming down at the bare metal can be challenging, especially since the BCM2835 documentation is limited.
For bare-metal real-time development, here are a couple of interesting new boards to be available later this month:
Texas Instruments Stellaris® LM4F120 LaunchPad Evaluation Board (http://www.ti.com/tool/ek-lm4f120xl) with a promotional price of US$4.99. The processor is an 80 MHz Cortex-M4F with DSP instructions, FLOATING POINT, 256KB Flash, and 32KB SRAM.
Freescale Freedoom Kinetis KL25Z development board (http://www.element14.com/community/community/knode/dev_platforms_kits/element14_dev_kits/kinetis_kl2_freedom_board) for US$12.95 with 48 MHz Cortex-M0+, 128KB Flash, and 16KB SRAM.