I have updated the ChibiOS/RT library to version 2.4.0.
This library is a simple way to use the ChibiOS/RT RTOS on 328 and Mega Arduinos.
The download is ChibiOS20120221.zip at http://code.google.com/p/beta-lib/downloads/list.
The main new thing for AVR is support for pal (digital I/O). If you want to try this edit halconfig.h and change line 47 to this.
#define HAL_USE_PAL TRUE
I have not tested pal, just checked that it compiles with the above define. A lot of edits will be required since the default board is a Olimex AVR-MT-128 proto board.
There are a huge number of internal changes. The diff between 2.2.8 and 2.4.0 versions of the utility folder in the Arduino library has 4739 lines.
There are a lot of new files. Most of the new files are for features not supported for AVR