Also compelling is the use of "ey" for "he" or "she", "eir" for "his" or "her" and "em" for "him" or "her". This system can be easily remembered by simply dropping the "th" from the associated plural forms (they, their, them) of each sexually dimorphised pronoun.
I like both of these solutions because they add more gender diversity to language rather than erasing it. Transgender is not about being non-gendered. It is about freedom of gender -- freedom far beyond the silly and oppressive two male-female poles of sexual dimorphism.