Beginning with iTunes 10.6.3 (OS X only), Apple implemented changes to iTunes' ability to respond to inter-app communications, causing calibre's 'Connect to iTunes' feature to fail. Some skilled programmers developed a workaround
for the 'appscript' library that calibre uses to communicate with iTunes. This workaround reenables the 'Connect to iTunes' feature beginning with calibre 0.8.58. This is a temporary fix; Apple has made it clear that they intend to limit inter-app communications in OS X for security purposes.
If you are unable to use the 'Connect to iTunes' feature, update to calibre 0.8.58 and try again.
If there is some additional news to report, I will update this post.
To discuss this issue, please use this thread
There is an existing calibre bug report here