CXF has a very different requirement profile than Mahout. People want to plug web service clients and servers into all kinds of environments, and get all huffy if forced to use something like Spring or Guice. Mahout, at this point in its career, at least, probably doesn't have this problem.
The interesting thing about the bus, I think, is that users are not required to interact with the IoC framework if they don't need anything exotic. I'm sure we could accomplish the same effect with Guice by being willing to require it. Thus, I'd be in favor of a Guice-ish backbone of some sort as a place to configure and park things like the RNG platform, but I'm really not on a campaign here, other than my personal belief that creeping static-ism just stores up trouble.
