When singular and plural aren't

My aunt pointed out to me a recent Scientific American article by Marc Hauser (the article link, unfortunately, only takes you to a teaser). Therein he points out that even though we think of the plural form of nouns being used for more than one, this isn't always the case.

We English speakers are somewhat inconsistent in what we decide to mark as plural. Allow me to illustrate: You is plural even when it refers to only one person. One megabit is singular even though it's 1,000,000 bits (or sometimes 1,048,576 bits). One apple is singular, but 1.0 apples is plural. Half an apple is singular, but 0.5 apples is plural. More than one apple is singular. And perhaps most confounding of all, zero apples is plural.

Hauser says this last is "actually ungrammatical" (I think that was the exact wording, though I don't have it in front of me.) Nonsense! It's perfectly grammatical. Just because the grammarians who chose the term plural for this part of our number system suffered from a lack of analysis/imagination, doesn't make the system wrong. Labels are not definitions, and they certainly are not invocations.