Updated: with images below.
Potential spoilers follow for Justice League #42.
Bleeding Cool reports tomorrow's issue, written by Geoff Johns, will reveal the identity of the Joker to Batman.
That appears to be true, but the kicker is - only to Batman.
Meaning not to the readers.
I don't have confirmation exactly what goes down this time, but a user on 4Chan (for what it's worth) states Batman apparently is told the Joker identity in which he says, "That's impossible," - meaning he knows who it is - and also questions the Moebius Chair about the identity of who killed his parents.
So the Joker's identity is not really revealed, and my guess is never will be.