OK, so I’m an idiot. 😳 Please scratch my previous two posts. (Ron, feel free to delete them!)
It was in fact a configuration error on my part (well, post-configuration – an accidentally deleted symlink to the iTunes xml file).
It is working fine with iTunes 6.0.5.
Incidentally, running with the -d option is what allowed me to finally track this down. Thanks for all the great debug output!