A phone call to HP Support got me a CD a few days later with the G85 All-In-One drivers for OS X. I understand there is an update on the HP web site now, but I haven't tried it.
I was able to install from that CD and (no thanks to HP support) can now use the G85 printer from OS X 10.1.2. I have also scanned in OS X. This is on a PowerBook G4 Titanium 400. My G85 is connected via TCP/IP using a JetDirect 300X. The TiBook is on AirPort.
HP support claimed that 'TCP/IP isn't supported' when I couldn't get it to work at first. I eventually figured out that I have to launch 'AIO Communications' (an HP daemon) manually, for some reason the installer didn't set it up properly to launch automatically.
I have seen a number of posts claiming very slow printing or 'screwing up' of their systems. None of those posts specified if they are using the printer over USB or TCP/IP. On my Mac, connected via TCP/IP, it works as quickly as I would expect, and has not 'screwed up' my system. Good luck.