The MacBook Air gets an update as well, with Ivy Bridge, USB 3.0 and more speed. All Ivy Bridge processors of up to 2.0 GHz, it will also start with 4GB of RAM, and the option to go all the way up to 8GB. Combine that with Ivy Bridge guts, and you've got a blazing thin monster with you.
It's SSD drive goes up to 512GB of space now, running at SATA 3 speeds of 6gb/sec. The MacBook Airs haven't gotten any smaller or lighter, but how much more could it have gotten that way? They're still great machines.