MagSafe 2 is a luxury reserved (so far) for the new MacBook Air and the Retina display-equipped MacBook Pro.

As you can see, the new MagSafe 2 connector (bottom) is much thinner and wider than its predecessor. This is pretty significant, because the thickness of Apple's devices seems to be limited only by the size of their ports.

Apple sells a $10 MagSafe 2 adapter, so you don't have to throw away your 27" Thunderbolt Display. Phew.

Apple never stops tweaking the details; they moved the symbols from the rear side of the ports to the front. If you're in a pinch and have to differentiate a Mid 2012 MacBook Air from a Mid 2011 model, just look at what side of the ports the symbols are on.