Matt,
I agree that tagging could become tricky if list is reordered each time a new selection is made. At most, it should be an option.
You may want to consider this different aproach: When user maintain pressed a key (CTRL, for instance) people list (or even any list) in panels could filter in order to show only tagged elements. This way, panels would work just like now in "normal" mode, but user would be able to see tagged elements by maintaing pressed the CTRL key. May be, left mouse button could be a better option. I don't know. (this way, tagging also could be tricky, but just for people who knows the trick
)
ITOH, the idea to group people is great, and it seems more necessary for this kind of product. Here is my suggestion:
A new "Data type" could be implemented for MC fields:
<<Hierarchical List (semicolon delimited)>>
"People" field would be this type, and it would allow to input this kind of content:
Family/Uncle Tom
Family/Mom
Friends/School/Peter
Friends/Alice
and so on.
Obviously, a new special panel would be needed: To show (and edit) the hierachy in a proper way.
I know you could group people in a easiest way: Creating the groups in MC Library, for instance. However, I like all information keep stored in the files (not just in the library).
Just an idea to consider.
Regards,
Polonio