The truth is that until last week the question had a clear answer: of course. In fact, Apple’s website for Time Machine announced this capability until last Tuesday, as can be seen in the cached version of the Google page:
Cordless and effortless. With a hard drive connected to your AirPort Extreme Base Station, all the Mac computers in your home can use Time Machine to back up wirelessly. Simply choose your AirPort disk as the backup drive on all computers and the entire family can enjoy the benefits of Time Machine.
But if you take a look at the current Time Machine page on Apple’s website, you won’t find such text. The closest thing is the phrase that indicates that you can use “another Mac that is running Leopard with File Sharing enabled.”
No longer planned to use the AirPort Disk feature with Time Machine? Taking into account how specific the original text was in this regard, the fact that this possibility has been purged on the new page does not look very good for those who would like to contemplate this option. However, the text at the foot of the previous version of the Apple website already indicated that the characteristics were subject to change.
Perhaps Apple decided that the performance of the AirPort Disk feature was not adequate enough, or some other problem appeared that suggested removing the text; if so, there is always the hope that it will add such a feature in a future update. However, next Friday we will know for sure if this feature has been removed in Mac OS X 10.5.0.