At a closed-door screening, Gearbox's Mike Neumann officially unveiled the previously described fifth character class, Gaige the Mechromancer. Unsurprisingly, Gaige more or less looks like her concept art as realized in the cel-shaded world of Borderlands. A very brief gameplay demo followed that introduced Gaige's main perk: a follower called Deathtrap that's sort of an apparition of a mech (however that works).
Deathtrap is a powerful, legless, floating robot that Gaige sends out to clobber her rivals, and he only gets more powerful as you upgrade your perk skill tree. At his most powerful form, Deathtrap looks menacingly spiky and can use a "Deathclap" skill that explosively sets his enemies on fire and/or electrocutes them.
The attendees of the demo also had a chance to watch an incredibly quick battle between the nearly impossible raid boss Terramorphous the Invincible and four of the devs. Neumann barely assured everyone that Terramorphous isn't even the biggest boss in the game before the massive tunneling creature made short work of the players and the gameplay demo was over.
Afterwards, we were all ushered to the main gameplay area of PAX to get the same hands-on that is open to the general public. Finally, I personally had a chance to check out Salvador the Gunzerker and had a blast double-wielding a variety of assault rifles and pistols against waves of enemies before I was tapped on the shoulder and asked to move on for the 50,000 other PAX attendees waiting in the two-hour line.