Version 2.2.x supports HA via live/backup server pairs using a shared store for the HornetQ journal, as discussed here in the documentation. It's not as convenient as the replication that will be available in 2.3, but it is still viable.
I'm not aware of any specific ETA for 2.3. We're working hard to get it ready for release ASAP.
we must release before major AS7. I have heard end of the year/// early next year.
so far It seems we will be ready. as the biggest features required are already in.