Along with the new Mac Pro, Apple has taken the wraps off a refreshed Macbook Air, the brand's ultra-thin and light laptop. The device is now powered by Haswell, Intel's fourth-generation core processor, which is said to offer up to 50 percent improved battery performance. The upshot: the 11-inch MacBook Air how has nine hours of battery life, the 13-inch featuring 12 hours. There's also a Wi-Fi boost in the form of ultrafast 802.11ac, plus 40 percent faster graphics courtesy of the Intel HD Graphics 5000. The 11-inch model starts at $999, the 13-inch model starting at $1,099. Both are available starting today.