That's the Schutt AiR XP, modified with Aaron's standard facemask.
Previously, Rodgers wore a classic Riddell shell. The external difference between the two is most noticeable in the construction of the side and shape of the earhole. Here's his old lid:
Going forward, the round ear hole will be the easiest way to identify pre-Week 16 of 2010 photographs of Rodgers.
From behind, the Schutt looks much the same as his old Riddell:
I hadn't noticed it before, but the Packers have moved the player identification decal off the center stripe. Looking through the archives, this tweak appears to have been made between Week 8 (at the Jets) and Week 9 (against the Cowboys).
Details on the new helmet are sketchy, other than vague reports that it is "specially modified with extra padding to reduce the risk of sustaining another concussion". It isn't clear if those "special modifications" refer to the off-the-rack Air XP, which was originally designed to minimize concussions, or if they're talking about custom modifications to the standard helmet.
Rodgers isn't alone in wearing the AiR XP; it has been seen on Donald Driver, BJ Raji and Sam Shields, among others.
Another interesting note on the Schutt helmet is the team branding on its nose bumper. Riddell is the "official helmet" of the NFL, which means that although players can chose from a list of safety-approved helmets, only Riddell helmets are allowed to display a manufacturer's logo. Teams fill the resulting empty space on non-Riddell helmets with their own iconography; the Packers use their stencil wordmark.
The difference can be seen on Rodgers's two helmets (the photo on the left comes from the October 17, 2010 game against the Dolphins):
Rodgers reportedly took some kidding from his teammates about the new shell:
"His helmet is just hideous, but you’ve got to do what you’ve got to do. It scrunches his face up pretty bad."
– wide receiver Greg Jennings
"He does have an ugly-looking helmet. But we’ve got him back."
– cornerback Charles Woodson
Rodgers's new helmet is one more step away from the iconinc "round-hole" Riddell look, which has defined the football helmet at least as far back as the 1970s. Renderings of the helmet are used as alternate logos by every team in the NFL.
The Cleveland Browns take it one step further, using this particular rendering as their primary logo.
The Packers, for their part, use the same graphic on all manner of team merchandise, everything from smokeless candles to this customizable sweatshirt:
I wonder what will happen as more and more players move away from the standard Riddell shell to different (and distinctive) profiles, if this graphic will be phased out of use or will begin to take on a "throwback" patina.