We hope to create a server which can either act as a more performant drop-in replacement for the vanilla server, or support mods written in Rust. The server side of the project is quite new and doesn't do anything yet.
The client uses the Piston game engine and can currently render a “frozen” version of a Minecraft world: you can fly around in it but not interact. Rendering is nearing pixel perfection for blocks. Eventually, we also want to integrate it with the server to provide a real singleplayer mode.