I feel that there are many contributions that Rubinius has made to the interpreter movement. a) the race for performance against other interpreters, b) the creation of an official "ruby spec" that defines what the ruby language is , and thus makes both the interpreters and the main language better and c) created a movement itself that has many different goals and target audiences.

But I don't think that Evan, Brian, et al.'s goals have been to replace but rather further the movement of Ruby.