There already is a project, Reia http://wiki.reia-lang.org/wiki/Reia_Programming_Language, which implements a Ruby like language on the Erlang VM.

Depending on what you like from Ruby, you could also check out Lisp Flavored Erlang at http://github.com/rvirding/lfe. IIRC Virding was one of the original creators of Erlang.