Eric - I was really surprised to be able to open and process my IQ180 files since early JUNE via ACR and they looked OK (in fact, looked great - I was only shooting ISO 35 though). Obviously that was not official, even undocumented, but it was great to be able to use ACR with this back and I'm looking forward to official support (I've never warmed up to Capture One).
I've heard that Phase One backs create a dark slide exposure for every shot no matter what the shutter speed - even those shorter than one second - but that ACR is not able to use this data and so the RAW file is more noisy at all ISOs when using ACR vs. Capture One. (this includes all Phase backs, not just the new ones I assume) I wonder if 6.5 will be able to take advantage of this?