While Leopard is a significant improvement over previous Mac OS X releases, it has some notable shortcomings. IPhone users, database developers, people still running Classic Mac apps, and folks who are obsessive about backing up will find some disappointments. Read on for a roundup of six Leopard problems.

Wireless backup using Time Machine: You can't use Time Machine with wireless AirPort Disks, according to Apple Insider. Time Machine is Leopard's slick backup and version-control software, allowing users to roll back files, folders, or the whole system to a previous date. It stores data on an external hard drive. Pre-release versions of Leopard allowed users to connect a hard disk to the AirPort Extreme Base Station, and use that hard drive and Time Machine to back up all the machines on a local network. But that no longer works in the final release.

SuperDuper support: The popular backup software will be updated to be compatible with Leopard "shortly after Leopard's release," the developers say.

Bootable backups using Time Machine: SuperDuper's developers note that, even with free backup built into Leopard, their software still has a role: With SuperDuper, you can boot your Mac directly from an external backup hard disk, which you can't do with Time Machine. In the event of a total system failure, you can just plug your external backup hard disk into a second machine and keep working while your primary machine is being repaired or replaced.

Syncing desktop Notes to the iPhone: This has been one of my chief frustrations with the iPhone -- there's no simple way to automatically sync plain-text documents between the iPhone and desktop. It's a baffling shortcoming: The iPhone is otherwise such a sophisticated device, with many advanced features, and this kind of note-syncing is brain-dead simple technology, available in the very first PalmPilot 11 years ago (and probably in other portable handhelds years before then). It's like finding out your cutting-edge, rocket-propelled sports car lacks windshield wipers. Early indications were that Apple would fix this lack in Leopard, but now it appears Apple changed its mind.

FileMaker support: The FileMaker database development app isn't completely compatible. FileMaker says, "FileMaker Pro 9 and FileMaker Pro 9 Advanced generally run on Leopard although there are two known issues. We are targeting a downloadable update to be available on Nov. 19, 2007."

Classic Mac OS X support: The 23-year-old OS won't even run on PowerPC machines running Leopard. It has never run on Intel Macs. Engadget quips that the only people affected by this will be "Hypercard user groups and the three printshops still running QuarkXPress 4."