Quicktime videos > iTunes > iPhone

I think in iMovie you can share the movie to iTunes. From there you should be able to sync it.

iMovie can make the mobile movie with the dimensions that will fit the iPhone and you will have two movies in iTunes if you want a full resolution movie and the mobile version. You can also create a mobile version by avoiding iMovie completely and exporting two movies (almost double the size). To do this you can refer to this thread. There are many other threads like this one, asking the same questions. Please search before immediately posting a new thread.

Regards,
David