I suppose those who actually want an apple PDA could read something into various recent events. Perhaps the fact that M$ has admitted that they haven't started working on an OS X version of Outlook provides some more, totally unsubstantiated, evidence?
One obvious 'missing' iApp in the digital hub is something like Outlook with an Apple spin (more intuitive, better looking, etc.).
This new iOrganize or iLofax or iDate application would handle all scheduling, e-mails, etc. It would be a mutation of the OS X Mail application. If you imagine the relationship between the old Image Capture to iPhoto, do the same to Mail and this is the new Application. What's the missing feature? The apple PDA which, to save Steve from being a liar, isn't a PDA (not a PDA because it's got a hard disk? because it's an iPod as well? Because it's an iPhone?).
I personally don't think an Apple-brand hand-held is coming (but that's probably because I don't want one). I do think the Application might be on the way... And that apple might develop it in conjunction with firms such as Palm, and improve the PDA scene through its influence.