We had this discussion on my blog once already.  But anyhow, since it's one of my personal grammar crusades, here's another article on the history of using "they/their/them" as the first-person singular instead of the contemporary but much more awkward "he/she" convention. 

"...for most of the existence of the English language, ‘they’ was used as the accepted singular gender-neutral pronoun. The use of ‘it’ was reserved for objects, as it is today, but for people the pronoun of choice was they/their/them.

So how did this all change? Courtesy of the English Parliament."

Damn Interesting » When They Became Him