I did JAX-EWR-BOS on a 45-minute connection last week, into C and out of A, and just barely made it -- and only because I could use the fast-track security line at Terminal A. If I had had to stand in the regular security line I would've missed my onward. Crazy. I don't see why there isn't an airside shuttle similar to what they used to lay on at IAH between E concourse and the ExpressJet terminal.