A while ago (sometime in August) I built a small service called [What Rust is it?](http://www.whatrustisit.com/).
Based on what [What Train is it now?](http://whattrainisitnow.com/) is for Firefox, this small service lists the three trains of Rust: release, beta & nightly as well as their respective versions.
It's updated every day and actually checks what `rustup` installed.
Additionally it shows the (planned) date of the next release.
Similar information is available on the [Rust Lang Forge](https://forge.rust-lang.org/).
