With the same performance, static protection against irreversible side-effects, and clever aversion of the privatization problem? I'm not aware of any. While STM can be theoretically done in any memory-safe imperative language, Haskell -- mainly because of its purity and type system -- seems to be the only language in which it can be fast enough and correct enough for practical use.

edit: well, Clojure restricts mutability too, so STM is sort of tractable there, but it doesn't get the other benefits that Haskell's type system gives you.