Update, Oct. 5: I've just been in communications with HP's U.S. public-relations agency again, regarding the driver and firmware updates that had been scheduled for release by summer's end.
Today's message is that the software is now expected "in the next few weeks." The person could not be any more specific, but did advise me to keep my fingers crossed. (Kind of difficult to use Photoshop in that position, but that's another story.)
Hope this helps.