the clobber passages - Leviticus 18:22

Leviticus 18:22 has long been used to clobber queer Christians: "Thou shalt not lie with mankind, as with womankind: it is abomination" as the King James version puts it. But what does the text actually say? Why does it say it? And should we care what Leviticus says when it bans polycotton shirts?