Yes, Rust and Servo both use libuv as the native async I/O layer. It's been fantastic for us as an easy-to-use API that works on Windows. Kudos to Ryan Dahl and Joyent for creating it.
Kudos should go to Bert Belder and Ben Noordhuis of Cloud9 who built much of libuv and Igor Zinkovsky of Microsoft has contributed a lot of important work as well. As well many other contributors.