Rust is moving towards stability:«The alpha release is part of our transition into stability guarantees. While we’re not ready to make full stability guarantees yet, this release cycle moves us much closer to that 1.0 goal. When 1.0-beta1 is released six weeks from now, these important remaining APIs will be stable. Code that compiles on the beta release should do so with minimal changes on 1.0 final as well.»
http://blog.rust-lang.org/2015/01/09/Rust-1.0-alpha.html
