I believe they said they were aiming for a '.5' release sometime at the start of this month once they're halfway done with Sinnoh, but that may have changed
I know what their doing. 4.1 will be all mythicals and sub-legends (- heatran). 4.2 will be the rest of sinnoh. They don't put aims because they dont want people to go and ask "you said update now, where update?"
Thats right, gen 4 (gen 5 will be the same) has so many legends that I decided to split it in half, partly so I could get an update out without too much waiting, but also so I can playtest the parts I have done better, since I have less to do I can pay more attention to them