RT-Thread RTOS is an open source real-time operating system for 16-bit and 32-bit microcontrollers, with components which include a hard real-time kernel, a command line shell, a device virtual file system, and a graphic user interface. RT-Thread RTOS 0.4.x series will be licensed under the Apache License v2.
RT-Thread RTOS 0.3.0 Released
Submitted by midnight 2010-04-19 OS News 2 Comments
From the linked article:
Object oriented real-time core (while remaining the elegant and flexible style of C Programming Language);
Object-oriented in C? Elegant in C?