The newly released Cobra 0.9 provides language refinements, library additions, new samples, new koans, an improved @help directive and expanded documentation. Of course, plenty of bugs have been squashed and locked out with an expanded test suite. See the official release notes for full details.
Cobra runs on .NET 2.0+ and Mono 2.6+. A JVM back-end is underway.
Cobra is a community-driven, open source project under the MIT license.