This is a work in progress, some features are implemented partially (most notably completion), there may be performance and stability problems.
Visit intellij-rust.github.io to find documentation about available installation options and features.
If you want to jump straight in, install IntelliJ IDEA, open
Settings > Plugins > Browse repositories,
install Rust plugin, and use project from existing sources action to import a Cargo-based project.
Unstable master branch builds can be downloaded from TeamCity.
Frequently asked questions, a.k.a. "Where is Rust SDK?", are on the website :)
If you are looking for the TOML plugin, see toml directory.
The plugin is compatible with any IntelliJ based IDE starting from 2016.2. If you don't have any yet, try IntelliJ IDEA Community Edition, it's free.
You're encouraged to contribute to the plugin in any form if you've found any issues or missing functionality that you'd want to see. Check out CONTRIBUTING.md to learn how to setup the project and ARCHITECTURE.md to understand the high level structure of the code base. Good first bugs are tagged with up-for-grab.