Apple has begun shipping Time Capsule, its latest external hard drive that is pretty much the only game in town if you want to do wireless Time Machine backups from your notebook.
Time Capsule was first introduced at Macworld. It's an 802.11n Wi-Fi base station with either a 500GB or 1TB hard drive that allows you to back up files to the drive or share files across a network without having to connect a cable. It will set you back either $299 or $499, depending on the storage size chosen.
It's a solid product in its own right (although stay tuned for CNET's review), but Time
Machine Capsule is actually a workaround for a feature in
Mac OS X Leopard that disappeared just before Apple was getting ready to ship the new operating system. In the runup to Leopard's debut, Apple advertised wireless backup features as part of Time Machine, the intuitive backup and recovery program that was included with Mac OS X 10.5.
But that language was pulled from the ad copy just days prior to Leopard's debut, and its disappearance has never been officially explained, as far as I can tell. As a result, there was no way to use Time Machine on a MacBook or MacBook Pro and an external hard drive without physically connecting the notebook, which is kind of a pain. You can set up wireless backups if you're running a Leopard server in your home, or if you set up a Xsan storage-area network, but those aren't really practical options for most of us.
It seems likely that the external hard drive itself needs some sort of extra intelligence to process the Time Machine handoffs over a wireless connection, requiring Apple to design Time Capsule with that updated firmware or software. Still, it would be a shame if Apple is unable or unwilling to add that capability into Leopard via a future software update, forcing anyone who wants to do wireless backups to buy Apple's hard drive.