In a few weeks (maybe sooner), NJ Transit will start running shuttle trains between Secaucus Junction (take the train from New York Penn to Secaucus Junction) and the new Meadowlands Rail Station for certain events.

When you refer to Arena, do you mean the Stadium or the Izod Center? For major events at the Stadium, there will be rail service to the Meadowlands from Secaucus Junction .

If the event is at the Izod Center or the Racetrack, there should be bus service from Secaucus Junction to the Meadowlands.

Check out this website and click on Schedules/Maps (if it is at the stadium) or Izod Center/Racetrack on the bottom:
http://www.njtransit.com/sf/sf_servl...=MeadowlandsTo