The wireless backup feature that disappeared from Apple's promotional copy for its Leopard operating system has snuck in through the back door.
Macworld did a little poking around with the recently released Mac OS X software update for "Time Machine and Airport" and realized that Time Machine now recognizes a generic USB hard drive plugged into an Airport Extreme base station, allowing Airport Extreme users to wirelessly back up their notebooks with Leopard's Time Machine. You need to mount the external hard drive using Finder to make sure Time Machine can see it, according to Macworld.
Apple had promoted this aspect of Time Machine--wireless backups via Airport Extreme and a USB hard drive--in its advertising for Leopard, the latest and greatest version of Mac OS X released in October. But at the last minute, that capability was pulled from Apple's ads, and Leopard early adopters found they were unable to use Time Machine with a notebook unless they plugged a USB hard drive directly into the notebook, or if they set up a complicated storage-area network. It was never clear what led to the disappearance of that feature, but perhaps the code just simply wasn't ready for prime time.
In January, Apple announced Time Capsule, a combination USB hard drive/wireless base station that allowed for wireless backups. But at $299 or $499, depending on the storage capacity, it's a pricey option for people who already own Airport Extreme and USB hard drives.
Time Capsule is a pretty easy way of getting the wireless backups up and running if you don't already have a wireless access point or USB hard drive. But if you bought Time Capsule to replace your Airport Extreme access points and USB hard drives, well, um, turns out you didn't need to do that.