Installed Lubuntu 12.10 on an ASUS EeePC 1000h last month. I downloaded the latest version of HPLIP (3.12.10a) for my HP d1660 printer and attemped to install.
I entered the following commands in the lxterminal;
rex@rex-1000H:~$ cd Downloads
rex@rex-1000H:~/Downloads$ sh hplip-3.12.10a.run

I got the following response:

HP Linux Imaging and Printing System (ver. 3.12.10a)
HPLIP Installer ver. 5.1

Copyright (c) 2001-14 Hewlett-Packard Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

Installer log saved in: hplip-install_Sun-11-Nov-2012_10:41:27.log

warning: CUPSEXT could not be loaded. Please check HPLIP installation.
rex@rex-1000H:~/Downloads$

Now what do I do? I have not installed HPLIP yet so there is nothing to check.

There does not seem to be any help on the HP site that I could find. Launchpad just confused me more.

Is Cups installed? If not, install it first. Is there some reason you did not install hplip from the repos?

CUPS is installed. I did not install from the repos because HPLIP 3.12.10a (the latest version) was not available and since Lubuntu 12.10 was just released I assumed (perhaps wrongly) that I might need the latest version. I have always downloaded HPLIP from the HP web site and things have always installed without any problems or hangups. It appears now after a little more research that the latest HPLIP does not support Lubuntu/Ubuntu 12.10 and will not support 12.10 until the next release, which I believe is 3.12.11 and may not be out for a couple of weeks. Thank you for the reply, but it appears that I am stuck until the next release. Fortunately, I am dual booting on this computer with Lubuntu 12.04 and HPLIP did install on that version and works quite well.

For all of you people in the same boat that I was in, HP has released HPLIP 3.12.11 and I installed it in Lubuntu 12.10. That took care of the problem.