After reading this thread, I have come to the conclusion that I have learned nothing new from what I already knew before about the differences between the Mogul and the iPhone. There are fanboys on both sides, and it's hard to get an unbiased comparison.

As for my biased opinion (just like everyone else's here), I think SpineDoc has the most significant statement in this entire thread... those who prefer substance over style will gravitate towards the Mogul. I know what it used to be like to have a 4" 640x480 Pocket PC screen. As you get used to it, the newness wears off, and you're left just wanting to add more programs and accessories. There's only so much that the iPhone can accommodate in that area.