Ben Yagoda notes a shift in American punctuation conventions:
For at least two centuries, it has been standard practice in the United States to place commas and periods inside of quotation marks. This rule still holds for professionally edited prose: what you’ll find in Slate, the New York Times, the Washington Post—almost any place adhering to Modern Language Association (MLA) or AP guidelines. But in copy-editor-free zones—the Web and emails, student papers, business memos—with increasing frequency, commas and periods find themselves on the outside of quotation marks, looking in. A punctuation paradigm is shifting.
Elizabeth Scalia wonders (with tongue in cheek) whether this shift (along with the gradual extinction of the semicolon) poses a threat to our way of life here in the good old US of A.
Do I have to sketch this out on a chalkboard? We’re seeing the migration of the comma outside the quotation marks — supposedly more logical than the alternative — at the same time as the gradual phasing out of the semicolon, which is seen, somehow, as both fussy and frivolous. I ask you, people (rhetorically, of course): Cui bono? Who stands to gain from this?
Actually, I have no idea. I’m a cruddy meme smith, as it turns out. But all of a sudden, I find I’ve gained a new sympathy for all those people who miss the Latin Mass.