• MacBook Air Update [1] from Apple resolves an issue where one of the machine's two processors would turn off if the temperature rose to a certain point, a feature Apple calls "processor core idling." To quote the other sentence in release notes that are downright loquacious for Apple, "Third-party software that modifies processor operating characteristics such as frequency and voltage is not supported and should be removed before installing this update." In other words, if you've installed software to help work around the "processor core idling" bug, remove it before installing the update. The update also addresses unspecified video playback issues. (Free, 368K)
• Mactracker 5.0.4 [2] from Ian Page updates the freeware utility that provides detailed technical information on a wide variety of Apple hardware with the latest information about the iPhone 3G, new fields for iTunes Version and Machine ID for iPhone models, and updated information for the support status of Apple's latest "vintage" and "obsolete" products. (Free, 20.7 MB)
• Keyboard Maestro 3.4 [3] from Stairways Software adds to the macro utility a Typed String trigger that executes actions whenever you type a particular sequence of characters, optionally deleting the typed characters as part of the process. Other changes are cosmetic, minor, or fix bugs. ($36 new, free update, 6.2 MB)

[1]: http://www.apple.com/support/downloads/macbookairupdate.html
[2]: http://www.mactracker.ca/
[3]: http://www.keyboardmaestro.com/