Charlie, on and off the train

The MBTA is introducing the new "Charlie Card" slowly, and with great fanfare. People getting on the T at Airport Station can (have to?) buy a Charlie Card and use it instead of a token or multi-day pass. But these cards are being phased in so gradually they expect it will take 2 years to get to the rest of the system. I'm not sure if "the rest of the system" means all the subway stations, or subway+buses+commuter rail. I think that's optimistic, from what I know of the T. I read something about them doing all the Blue Line stations first, then Orange, then Green, and finally Red. The vast majority of my MBTA riding (and those of people who might come to visit me) is on the Red Line and buses, so I don't anticipate much need for a Charlie Card until 2008.

The nice person coming to visit this weekend will be traveling through the airport. And then, most likely, through the Airport T station on the Blue Line. Will the Charlie Card be useful for taking other parts of T this weekend? Later this summer? Or is it just a very elaborate way to buy one ride from the Airport Station, while entry from every other point needs coins or tokens?