How do I get my iphone to show up in iTunes 11 consistently? I upgraded to iTunes 11 today and my iPhone rarely shows up in iTunes. It almost never does through wifi (even though wifi syncing is on) and if I connect it with a USB cord, I have to restart the iphone for it to recognize that it is connected.

What could the problem be? (iphone is not jailbroken and has latest iOS and Itunes is just updated) and how could I fix it?
This happens to me, too.  The computer is connected by ethernet to the wifi router.  Sometimes exiting iTunes and the re-launching works to get iTunes to see the iPhone.  (And connecting the iPhone to the computer by cable always works.)