Originally Posted by
milepig
To clarify, the train I referred to does not go from CDG to Paris. It is a shuttle within the airport that you can take to get from your terminal to the RER train, which does go to Paris.
The shuttle train is a couple of years old. I used the term "new" since I haven't taken it (and, I am, of course, the center of the universe), and also in the context of an airport that takes years to renovate a terminal (eg #1) or repair one that's damaged (eg, 2E).
I haven't caught the RoissyBus from T1 (avoiding T1 is high on my list of things to do in Paris) but in T2 there is good signage.