This feature has been discussed in the AI pre-release thread as well as
other FR threads.
Item notes is a very useful feature for storing all kinds of information about a media item. Users can type notes, and scripts can store any information that can be encoded into strings.
AFAIK there is no other way to associate information with media items so that it remains associated with all copies and child items after copying and splitting.
Item notes will be similarly useful for automation items.
In particular, envelope scripts such as Xenakios and my LFO Tool could then store an AI's curve data inside the AI itself, recall it whenever a user wants to re-edit the AI, and the data won't get lost during moving and copying.