I've heard about that a couple of times but it's not easy to find the reason.

Please check the following things:
- use "about:buildconfig" and paste the "configure arguments"
- use the command "readelf -s /usr/lib/xulrunner-1.9/libxul.so | grep cairo_ps"
  and paste its output
- use the same readelf command on libcairo.so (find the detailed name by 
  following the symlinks)

1.
about:buildconfig

Build platform
target
i686-pc-linux-gnu

Build tools
Compiler 	Version 	Compiler flags
gcc 	gcc version 4.3.1 20080507 (prerelease) [gcc-4_3-branch revision 135036] (SUSE Linux) 	-Wall -W -Wno-unused -Wpointer-arith -Wcast-align -W -Wno-long-long -pedantic -march=i586 -mtune=i686 -fmessage-length=0 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -O2 -g -Os -fno-strict-aliasing -fno-strict-aliasing -pthread -pipe
c++ 	gcc version 4.3.1 20080507 (prerelease) [gcc-4_3-branch revision 135036] (SUSE Linux) 	-fno-rtti -fno-exceptions -Wall -Wconversion -Wpointer-arith -Woverloaded-virtual -Wsynth -Wno-ctor-dtor-privacy -Wno-non-virtual-dtor -Wcast-align -Wno-long-long -pedantic -march=i586 -mtune=i686 -fmessage-length=0 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector -O2 -g -Os -fno-strict-aliasing -fno-strict-aliasing -fshort-wchar -pthread -pipe

Configure arguments
--enable-application=xulrunner --prefix=/usr --libdir=/usr/lib --sysconfdir=/etc --mandir=/usr/share/man --includedir=/usr/include --enable-optimize --enable-extensions=python,default --with-system-jpeg --with-system-zlib --enable-xft --disable-freetype2 --enable-svg --enable-canvas --disable-tests --disable-mochitest --disable-installer --disable-javaxpcom --disable-crashreporter --enable-startup-notification --enable-url-classifier --with-system-nspr --with-system-nss --enable-system-cairo --enable-system-hunspell 


2.
SuSe-pvn:~ # readelf -s /usr/lib/xulrunner-1.9/libxul.so | grep cairo_ps
  1058: 00000000    98 FUNC    GLOBAL DEFAULT  UND cairo_ps_surface_restrict
  1783: 00000000   109 FUNC    GLOBAL DEFAULT  UND cairo_ps_surface_create_f

3.
readelf -s /usr/lib/libcairo.so  |grep cairo_ps
   274: 0002e470    94 FUNC    GLOBAL DEFAULT   11 cairo_ps_surface_set_size
   284: 00031660   128 FUNC    GLOBAL DEFAULT   11 cairo_ps_surface_create_f
   285: 00031910   135 FUNC    GLOBAL DEFAULT   11 cairo_ps_surface_create
   309: 0002e3a0   106 FUNC    GLOBAL DEFAULT   11 cairo_ps_surface_dsc_begi
   474: 0002e410    90 FUNC    GLOBAL DEFAULT   11 cairo_ps_surface_dsc_begi
   488: 000313b0   253 FUNC    GLOBAL DEFAULT   11 cairo_ps_surface_dsc_comm

forgot to mention is answers NEEDINFO

Ok, apparently the issue is (I'm a bit wondering why it doesn't create an error at compile time though):
Firefox is using cairo functions not available in cairo 1.4.x
(cairo_ps_surface_restrict_to_level)

We need to use the builtin cairo for 11.0 and older.

I just found that the packages provided by me in OBS are correctly not using system cairo on 11.0.
Apparently a fix Novell didn't take to their packages :-(

Something is fishy. According to the spec "--enable-system-cairo" shouldn't be set on 11.0. Will need to investigate why it is used.

ok, just to be sure we'd need the following information:

The complete output of 
rpm -qi mozilla-xulrunner190

SuSe-pvn:~ # rpm -qi mozilla-xulrunner190
Name        : mozilla-xulrunner190         Relocations: (not relocatable)
Version     : 1.9.0.8                           Vendor: openSUSE Build Service
Release     : 19.1                          Build Date: Fri Mar 27 11:09:10 2009
Install Date: Thu Apr  9 14:16:14 2009      Build Host: build10
Group       : Productivity/Other            Source RPM: mozilla-xulrunner190-1.9.0.8-19.1.src.rpm
Size        : 18960642                         License: GPL v2 or later; LGPL v2.1 or later; MOZILLA PUBLIC LICENSE (MPL/NPL)
Signature   : DSA/SHA1, Fri Mar 27 11:12:45 2009, Key ID af428e87330d83be
URL         : http://www.mozilla.org
Summary     : Mozilla Runtime Environment 1.9
Description :
XULRunner is a single installable package that can be used to bootstrap
multiple XUL+XPCOM applications that are as rich as Firefox and
Thunderbird.


Authors:
--------
    Mozilla Foundation <drivers@mozilla.org>
Distribution: home:Fisiu / openSUSE_11.0

Ha, sorry, this is invalid then for openSUSE.
You are using a package from OBS:home:Fisiu. If you do that you would need to use also the cairo package from there but nothing I would recommend.

euhm.. Ok. so .. what do i do to get printing working again?

make sure you install mozilla-xulrunner190 and MozillaFirefox from the official update repository (or alternatively from OBS' mozilla repo).
The versions tab in YaST's software installation menu will show you the alternative versions.