As I suspected, the lack of voice dialing on the iPhone is going to be tackled by third-party developers. Here’s the first entry into the area that I’ve found: iSpeak.
“To be forewarned and therfore forearmed...is eminently rational if our belief is true; but if our belief is a delusion, this same forewarning and forearming would obviously be the method whereby the delusion rendered itself incurable.” <C. S. Lewis>