I heartily disagree with datajack. I use this expression whenever I'm writing and have to use a third-person subject pronoun where the gender of the subject is unknown or irrelevant or, most often, both. It works well in writing because you don't have to read it aloud and it even if you do have the reading style where you pronounce words to yourself, it's still okay since it's pronouncable. It avoids sexism, using plurals for singulars, and other problems.

Ideath, that's a great idea, but engineering a language like that seldom works - ask the French.