Recently Mitsubishi announced their CP-K60DW-S photo printer. Outwardly it is identical to their existing CP-D70DW, except for the use of red labels instead of grey. Beyond that, it appears to be functionally equivalent (even uses the same media) to the CP-D70 series, although not as fast.
This morning I dug into the spool file format the CP-K60DW uses. It's almost identical, though different enough to be annoying. Most of the changes had to do with print sizes; they're all slightly different, and there's support for 6x6 prints (but not the 6x9 the CP-D70x supports)
Some judicious decoding later, and Gutenprint now theoretically supports the CP-K60DW-S. Of course, lacking access to one of these printers I have no way of testing this, and can only hope its command stream is identical.
In the process I discovered and fixed a couple of bugs relating to command padding on the the CP-D70 series. Anyone out there with access to any of these printers (Mitsubishi CP-D70DW, CP-D707DW, CP-K60DW-S) that's willing to help me out?