The problem was apparently in the CD/DVD settings in System Preferences where iTunes was set to open automatically when a music CD was inserted. It appears that, in Lion, connecting Bluetooth headphones is the same as inserting a music CD. Changing that setting to "ignore" solved the problem.
None of that works for me. I've tried every suggestion I've seen here and elsewhere on these forums. Nada. I've even tried upgrading from OS X 10.6 to 10.8. There are several other events which will also launch iTunes and autoplay, always to my great annoyance.
I did write a perl script (posted in another thread) that kills iTunes when it tries to launch, that's the closest I've found to relief. If it wasn't for that, I'd have removed iTunes entirely.
It's even worse on my iDevices. Those have crossed the "annoyance event horizon" and I just removed all my music. Isn't that awful? Thank God they tore podcasts off into a separate app. Genius idea, make podcasts out of all my albums.
I have found a good workaround to this. Download the app Event Scritps. This allows you run scripts based on events. So when bluetooth device connects quit itunes. I have actually selected the option to quit itunes when itunes launches becasue i never use itunes. works well. Make sure itunes isn't going to open in fullscreen mode to ensure it doesn't bother you at all.
MB Air 2012
Plantronics Voyager pro
latest version of Event Scripts