I updated the extension by adding back the smb backend symlink to samba that got lost from the previous extension.
I tested the latest extension in two ways:
1. Directly connected to an hp usb all-in-one printer using cups+hplip
the cups browser interface finds the printer automatically and prints without problems.
2. Remotely connected to the same all-in-one printer shared by cups over a local network.
the cups browser interface does not find the shared printer, but the following command added the shared printer, which printed without problems thereafter: $ sudo lpadmin -p OfficeJetG85 -E -v ipp://192.168.1.100/printers/OfficeJetG85note that an error in cupsd.conf may be preventing the browser interface from seeing the shared printer.
As the cups usb backend cannot print to hp all-in-one printers, I cannot test it, so I'd appreciate feedback from users with usb printers.
To aid in trouble-shooting, here's what I get for a number of related commands: $ lsmod | grep usb
usblp                   6556  0
$ lsusb
...
Bus 004 Device 003: ID 03f0:0211 Hewlett-Packard OfficeJet G85
$ ls -l /dev/bus/usb/*/*
...
crw-rw-r--    1 tc       staff    189, 385 Oct  9 13:18 /dev/bus/usb/004/003
$ /usr/local/lib/cups/backend/hp
direct hp:/usb/OfficeJet_G85?serial=SGG13E0C49VL "HP OfficeJet G85" "HP OfficeJet
G85 USB SGG13E0C49VL HPLIP" "MFG:Hewlett-Packa;MDL:OfficeJetG85;
CLS:PRINTER;DES:OfficeJet G85;SN:SGG13E0C49VL;"
$ sudo /usr/local/lib/cups/backend/usb [cups-1.4.1 usblp loaded or unloaded]
DEBUG: list_devices
DEBUG: usb_find_busses=5
DEBUG: usb_find_devices=12
$ sudo /usr/local/lib/cups/backend/usb [cups-1.3.8 usblp loaded]
direct usb://HP/OfficeJet%20G85?serial=SGG13E0C49VL "HP OfficeJet G85" "HP 
OfficeJet G85 USB #1" "MFG:Hewlett-Packard;MDL:OfficeJetG85;
CMD:MLC,PCL,PML,SCL;CLASS:PRINTER;DESCRIPTION:Hewlett-Packard OfficeJet G
Series;1284.3M:f7f,f7f;1284.4DL:4d,4e,1;SERN:SGG13E0C49VL;VSTATUS:$HB0$NC0ff,
DN,IDLE,CUT,K1,C0,SM,NR,KP000,CP029;AiO:0;DW-PCL;"
Title:          cups.tczl
Description:    cups printing system
Version:        1.4.1
Author:         see list of sites below
Original-site:  see list of sites below
Copying-policy: see list of sites below
Size: 2.91MB
Extension_by:   juanito
Comments:       cups, the standards-based, open source printing system..
                ..developed by Apple Inc. for Mac OS X and other UNIX-like..
                ..operating systems
                ----------
                requires the expat2, dbus and libcups extensions
                if the expat2, dbus and libcups extensions are loaded in..
                that order, the cups daemon will automatically start.
                ----------
                howto:
                the root password needs to be set perform admin tasks with..
                ..the browser interface
                http://localhost:631 will start the browser interface
                To persist across boots, add the following to your backup:
                /usr/local/etc/cups/ppd/HP_OfficeJet_G85.ppd [for example]
                /etc/cups/printers.conf
                /etc/cups/cupsd.conf (only if you changed it)
                ----------
                This extension contains:
                cups-1.4.1 - GPLv2 - http://ftp.easysw.com/pub/cups/1.4.1/cups-1.4.1-source.tar.bz2
Change-log:     2008/09/06
                Updated menu item/icon
                Added smb backend for samba
                Added cups windows drivers in /usr/local/share/cups/drivers
                2009/01/30
                Modified foomatic filters for perl in /usr/local/bin
                2009/03/13
                upgraded to cups-1.4 and added start-up script
                compiled to use dynamic printer drivers
                removed foomatic-rip, split out libcups
                2009/09/16
                updated 1.4 -> 1.4.1, moved /etc/cups -> /usr/local
                2009/09/22
                added samba backend symlink
Current:        2009/10/09