Straight through Final Cut is the fastest way, I agree. If you want to get your hands on the files first though, Image Capture is the fastest way to get the files off your iPhone outside of Final Cut.
Some people like to organize their files in a certain way. There are also other programs that one might want to use. Having a central location for the footage is then an advantage.
That's nice but how do you import iPhone 4 videos that are no longer on the iPhone (i.e., from Aperture library). It's retarded that a question this basic requires a trip to the user forums.