Today's Macworld Expo keynote promised "something in the air," but the highlight actually came from a business-sized envelope during Steve Jobs' presentation. We'll have more in-depth coverage soon, but for now here's a rundown of this morning's developments.

Catch Some Air -- The new MacBook Air, dubbed the world's thinnest laptop, is a half-inch thick portable with a full-size keyboard, 13.3-inch LED screen, 1.7 GHz or 1.8 GHz Core 2 Duo processor (extremely small and custom made by Intel for Apple), 80 GB hard disk (with an optional 64 GB solid state disk drive also available) - and no optical drive or Ethernet port. It's available for pre-order today starting at $1,799, and shipping in two weeks.

Movie Rentals -- Jobs also introduced a movie rental service through the iTunes Store, with features available for $2.99 ($3.99 for new releases), and high-definition movies for just $1 more. After renting a title, you can keep it for up to 30 days; once you begin watching it, it expires after 24 hours. The movies can be synced to an iPod, Mac, iPhone, or Apple TV, too. Powering this is iTunes 7.6, which is available now via Software Update.

iPhone and iPod touch Software Update -- On the iPhone front, a software update available today adds smart location tracking to Google Maps, Web-clipping capabilities, a customizable home screen, the ability to send SMS messages to groups, and chapters and other features to video playback.

iPod touch owners can pay $20 to upgrade to a version of the operating system that includes the same applications as the iPhone (Mail, Maps, Stocks, Notes, Weather) as well as the improvements found in the iPhone.

Apple TV 2.0 -- To handle the new iTunes movie rentals, Apple introduced Apple TV 2.0, a free software update for existing Apple TV owners that untethers the set-top box from your computer. It can order content directly (which then gets synced to your computer), including high-definition (HD) content. The update will be available in two weeks. Apple also reduced the cost of the Apple TV itself to $229 for new buyers.

Time Capsule -- When Mac OS X 10.5 Leopard was introduced, one capability missing from the Time Machine feature was wireless backups, something that had been demonstrated months earlier. Apple made up for that today by introducing Time Capsule, an AirPort wireless base station that includes a "server grade" hard disk of either 500 GB ($299) or 1 TB ($499) capacity for wireless Time Machine backups.