Recently I tried to build a rust project (just to play a bit around with the language and the tool). The code was too new to build with the latest stable (0.7) but too old to build with the latest nightly. Servo (web rendering engine) even says which git version of rust to checkout to be able to build it.

Rust is at the moment not usable for productive code. They are still experimenting and changing things quite drastically. But I think that's a good thing. I'd rather wait another year for Rust and have a mature well-thought-out language. I've waited long enough for something like Rust I can wait a little longer.