FreeRTOS ports/demos for ARM 7/9/Cortex M3> download code
FreeRTOS is a popular (6K to 7K downloads per month) open source mini real-time kernel designed for use on microcontrollers. Nineteen architectures are supported in total—this download includes only ARM-related ports and demos.
The download includes demo projects for GCC, IAR, CrossWorks, and Keil compilers.
See http://www.FreeRTOS.org for a description of the directory structure plus lots more documentation and information about licensing.
The source code is small and simple—the download is a little large because of some of the libraries it contains.
Free support is available through an active support forum—http://sourceforge.net/forum/forum.php?forum_id=382005. Commercial licensing and support is also available for those that desire it.