For Apple to build a phone as slim as the iPhone 5, it needed a trimmer dock connector, which meant the venerable 30-pin dock on earlier iPhones (and iPod and iPads) had to go. The new Lightning connector has an all-digital, 8-signal design, and is 80% smaller than its 30-pin predecessor. Apple says it's more durable too. One nice touch: Lightning is reversible, so there's no wrong way to plug it in.
Of course, Lightning is bad news if you're planning to upgrade to the iPhone 5--and bring along your collection of iPhone accessories that use the 30-pin connector. The solution: Apple will sell a Lightning to 30-pin adapter, reportedly for around $30.