I have expected the Macworld keynote's time constraints would prevent an iPhone announcement. With an emphasis on Leopard alongside the standard keynote sections, including Adobe's demo of Photoshop, the time left for new hardware will limit the number. Jobs always limits genuinely new hardware announcement to one. This is a standard marketing practice. I'm sure the iPhone will be announced at a separate event beit before or after Macworld. Macworld announcements will disappoint many speculating websites and stock analysts while making the Apple stock shorts smile.
Two things:
1. If the iPhone has to become public due to FCC registration, then I can see the need for a pre-announcement, but not necessarily before Christmas except...
2. If the 4GB iPhone is priced significantly higher than a 4GB nano, let's say at $399, then I'd see it being possible. Otherwise, it would just freeze the still many iPod-for-Christmas-gift purchases.
The MacWorld keynote does look crowded, but Apple will need that in order to create a lasting buzz since it's directly up against CES this year.
Commenting by HaloScan
