Pico Windows - простой ГУЙ для eCos, uClinix; ориентирован на 1-битную графику http://sourceforge.net/projects/pwlib/
PW is a small graphics and windowing library. It was designed especially for small embedded systems using 1 bit graphic LCDs. It is very portable, written in ANSI-C and has a small memory footprint.
* Development Status : 5 - Production/Stable
* Operating System : eCos, uClinux
* Programming Language : C
Скорее всего, портировать под uCOS и другие "простые" embedded OS будет не трудно.
Выловил в мейл листе eCos.