I'm not sure what is going on, but I have now downloaded new firmware (v.xxxxx.07), Postscript driver (v.4.1.1) and printer utility (v.3.1) for my printer, a 44" Z3100ps GP. Everything seems to work like a charm (knock on wood!) so far. I even used a new paper preset to print a beautiful image with Harman Gloss with no roller marks (see the Harman Gloss thread for more details).
I know that the website is challenging to navigate at best, but when I just looked, the PS driver, new utility and the v.07 firmware were still up for the Mac PS version, as well as the Windows versions (driver 61.71.841.0 and print utility 1.4). It doesn't look like there is anything new posted for the non PS printers, though. The non-PS versions were up earlier today?
The new driver functions just as the PDF bulletin said, with obvious differences right off the bat in the second screen of the print dialogue box. Under Image Quality>Paper Type, the default is now "Any", with gloss enhancer now an option for any paper. I have no idea, though, if there is an advantage to selecting a specific paper type in this drop down menu. For the Harman Gloss I just tested, I chose a specific paper type since I didn't want to push my luck yet.