When Phoenix first started laying out plans for their modern light rail system they were only projecting some 25,000 weekly riders. It turns out that since they opened up a 20 mile line with 28 stops last December they’ve been seeing a ridership of 40,000 per week instead. this ridership is beating all the forecasts which would seem to indicate that there is more of a desire for public light rail transportation than previously thought.
The current rail line (the dark purple in the graphic – courtesy of Treehugger) actually goes through 3 cities: Phoenix, Mesa, and Tempe. The dotted purple line is the North-West extension that is scheduled to open sometime on 2012, as well one extension planned might include Glendale as well.
Here is a short video courtesy of StreetFilms highlighting the light rail system. You might also note that they have included bike racks on the cars in order to encourage multiple forms of travel as well.