Had to kill and reastart cupsd. Had a problem with Laser printer on parallel port -- seems to spit the dummy quite often.
Had to reboot eventually.
Now, although kprinter works, and kde print manager lists all my printers, no gnome apps have a printer list (apart from Postscript and Pdf).

Should there be real printers mentioned in /opt/gnome/share/gnome-print/?

Open office also no longer has the printer list it had yesterday -- bit I can print using kprinter.

Where do apps look for a printer list? I expected it would be in printers.conf or printcap, but obviously not.

Fixed
by fiddling with the Cups configuration in Yast.
Don't really know how, or why it had such a fit in the first place.