Apple quietly introduced a newer, slimmer, snazzier MagSafe connector here at WWDC, with the Retina display-equipped 15-inch MacBook Pro (yeah, the "next-generation" one) and the newly-unveiled MacBook Air machines utilizing it. Still, the original MagSafe is finding its way onto the refreshed MacBook Pro (both 13- and 15-inch), but we're guessing the original isn't long for this world. As with anything, change ain't easy -- for the two to talk to one another, you'll need an optional $10 adapter (which evidently ships gratis with the 27-inch Thunderbolt Display). It's also worth noting that the actual AC power plug returned to the "T-style" form factor, rather than the "side-style" seen in the MacBook units that were new... well, yesterday. We stacked a next-gen MBP atop a last-gen MBP just to showcase the differences; hit the gallery below if you're interested in such things.
Apple MagSafe vs. MagSafe 2: product comparison shots at WWDC 2012