Lately the term SaaS became a broader term and now it is called Cloud Computing (see David Chappell’s paper and Wikipedia). It includes the whole paradigm of utility computing + saas + platform as a service + * as a service.
I’ve got good feedback on the taxonomy map from the blogsphere (including Jeff Kaplan, from THINK IT Services). I updated the map some time ago but didn’t have time to publish. So here it is rather sooner than later. (I need Pablo’s help to do the animated GIF, so this time is static)