The Musical Comma: Teach the Controversy

I am creating an online copyediting course. The convention of this course is that each week contains a Discussion topic about which students can post on the class Discussion board.

The topic for Week 3 is Punctuation. So, I get to come up with a punctuation-related discussion topic, for copyediting students.

The hallmarks of a good discussion question are as follows:

• It must be open-ended, to allow for a variety of opinions. Questions that allow for a simple "yes," or "no," do not really provoke great discussion.

• It must have sufficient breadth to allow for a variety of opinions. If there is only one right answer, there's not a lot of room for discussion, and the students who post later on in the week can really only say "me too!"

• It must actually be germane to the topic at hand.

So, Internets, what do you think I should set as the week's discussion topic for punctuation?

The semicolon: marker of an outmoded elite or undervalued shorthand?

Who will save the apostrophe? How?

Who really cares about em-dashes?

All suggestions gladly welcomed. Suggestions that actually provoke discussion will be entertained.

ETA: Stuff like Emily Dickinson's Punctuation: The Controversy Revisited is alas beyond the scope of my course. I am toying with a "how do you balance the needs of your author's artistry with the conventions of punctuation"-type question, but I don't want to have to write an entire idiosyncratically punctuated ms.