I agree that competition is good. There is (was) concern that loud, shallow, infantile arguments of Merb versus Rails were damaging, to an extent. If nothing else, they were really, really annoying, and too frequent. This may be the "splintering" of which john_dahl was speaking.
There are other frameworks, although they get little "press", as they lack an Engine Yard or 37signals hype-machine. In fact, if you visit ramaze.net (one of the more mature frameworks) and scroll down, you can find a listing of all the frameworks of which the ramaze people are aware. Twenty-one, including Merb AND Rails, at last count. (It is likely that not all of them are wholly distinguishable from one another. I can't say, as I haven't tried them.)