[matthiaskramm]

We're planning to keep this running indefinitely.

We may also add additional languages in the future, like Haskell and Lua, and possibly some advanced playing modes.

[eridius]

Might I suggest Go? It's already sandboxable, demonstrated by the "Try Go" box right on the front page of golang.org.

[sofuture]

Count this as a vote for more languages.