4e class roles system has, for our group, been a very good thing. It's similar, in its broad strokes, to the way MMO's organize their classes. They map almost exactly to the archetype set-up of City of Heroes, my MMO of choice; the execution of each role is quite different, and CoH breaks strikers down into melee and ranged, but the basic structure of tank, damage dealer, buffer, and debuffer is the same in both games. I'm told that World of Warcraft has a similar system, though I don't have any direct experience with it.
The advantage for us is that half the group has played various MMOs, and the other half is familiar with the basic principles and with similar ideas in other video games. It was very easy for the players to understand the basic sorts of things that each class could do, how they should be played, and how they interact with each other. We're learning the finer details in play, but the basic structures are familiar.
This'll be a bigger deal with new players. Not all the people I've taught to play D&D have been video gamers first, but a lot of them have been; the interest areas do overlap. And these days, if a video gamer doesn't play an MMO, chances are good that they know someone who does, or have played a game that borrows some of that class architecture. That D&D now uses some of this common language may make it more familiar to these people, its outlines easier to understand, and provide some common reference points to aid in my explanations of the system.