We aren't using the type of maglev that's used in maglev trains where the track is magnetized and super expensive. We're using ArxPax hover engines[1]. They just spin a Halbach array[2] super fast and generate a hovering force off of an aluminum track.
The winning team of Design Weekend last January, MIT, is also using magnetic levitation but they are doing a passive version. The track still isn't magnetized, but their magnets generate their eddy currents just by the movement of the pod. It sort of "takes off."
The first reason we -- and others in the competition, though not the majority I believe -- went with maglev is that the we (well, the Mechanical Engineering students, I'm CS) couldn't find air-skis that worked at high speeds. Elon mentioned at Code Conference that they'd been tested up to Mach 1.1 but when I told the ME's of that they said they hadn't found anything they could use nor any research showing that the air being pushed out of the ski "keeps up" with the pod at high speeds.
In addition to the speed problem with air skis, they also hover much lower off the ground than the maglev and require much higher tolerances on the track (more expensive).
Part of the reason to have the competition is to try a bunch of different ideas at once and see what works best. I do believe there are plenty of teams that will be testing air-skis on the track at competition weekend. We'll see how it goes.