Promising new programming languages

It seems like these days there are lots of programming languages springing up. A combination of the web, parallel programming, and just outright curiosity seems to be fueling creativity towards new mixtures of classic features and experimental new ones.

Here are a few new(-ish) projects I'm keeping my eye on:

Rust (Mozilla Research) - Concurrent language that only allows sharing of mutable state if it's handed off between threads. Uses typestates to enforce this ownership. Expected to be used in Project Servo, Mozilla's experimental parallel browser engine. Recent talk slides look promising. Still experimental (haven't reached 0.1 yet).

Kotlin (JetBrains) - Impressively clean/lightweight syntax language for the JVM in the spirit of a Scala light. Perhaps may be to Scala what Firefox was to Netscape, but it's not yet release so it's hard to say for sure. Still, their presentation at the JVM Language Summit is worth a watch.

ooc - You have to like the infectious audacity of this project. Hobbyist putting together a language, then proceeding to write one compiler for it in itself and then another.

Dart (Google) - Mentioning it here because I'm curious, but the hype has already overshadowed it. We're still weeks away from knowing anything about it. Still, Gilad Bracha is like a "curiously strong mint", so we at least know it won't be flavorless.

These are just the ones on my radar. There are certainly others (Ceylon, Gosu, Mirah - and those are just the ones on the JVM), but they haven't quite made it to my twitter follow list.