There is probably much more than this, but the only thing new officially mentioned on the forum is this:
New feature -- plays unencrypted betas and arcade games.
still doesn't emulate JAMMA...
One forum user had this to say though (hope he doesn't mind my repeating it here):
The new versions seems much faster, then again I only got 4 games to check!! nfs, space hulk, return fire and road rash. Still a few graphic problems but it runs real smooth.
Please give feedback in their beta forum (see link at top of message).