This is my NesC UART driver for ATMega128. Most of the files were imported from TinyOS (I hope they don’t mind, since it’s BSD license anyway). You can download it from here.
I haven’t tested the whole code yet, but I’m pretty sure that it’ll work just as it is (since it’s already work inside TinyOS).
Anyway, my next target after this is to provide buffer for Tx and Rx, just like the Peter Fleury’s UART library.