hplip-**.xzm (13MB)
-the biggy, includes hpijs.The most recent version is to be found in .rpm form.
printer-driver-hpcups_3.12.6-3.1_amd64 (313 kb)
-same drivers as in hplip but stripped off. It is supposed to be ppd's excluded. Comes from .deb.
hpijs-3.12.4-4.el6.x86_64.xzm (MB)
- for hp inkjet printers. Some included in hplip or printer-driver-cups, others not. Comes from .rpm, if you want the most recent version.
Some more hp drivers package to come.
Enough for tonight and maybe this week.

Note: Compared to hplip and printer-driver-hpcups, gutenprint seems to cover more widely all the manufacturers, but less the hp manufacturer. Which seems a valid conclusion.