Two years ago I wrote an article about working with JSON in Rust. JSON (de)serialization support was then baked in the standard library. However, at that time Rust was at version 0.13 and a lot of things happened since then. Mainly, the rustc-serialize crate got pulled out of the core libraries, but kept its close relation to the rustc compiler itself. (Hence the slightly awkward name.)

Meanwhile, a new contender arose: serde. It is also a generic serialization framework for Rust. It's more modern, actively maintained and gets lots of love from the community. There's a selection of supported data formats, including JSON, YAML, MessagePack as well as several others. Even the official docs for rustc-serialize say (emphasis mine):

While this library is the standard way of working with JSON in Rust, there is a next-generation library called Serde that's in the works (it's faster, overcomes some design limitations of rustc-serialize and has more features). You might consider using it when starting a new project or evaluating Rust JSON performance.