1. CUPS shows the printers as present and accepting requests.
2. Same for lpstat
% lpstat -a
Cups-PDF accepting requests since Wed 09 Jun 2010 07:25:25 AM PDT
lexmark accepting requests since Mon 01 Aug 2011 11:49:38 PM PDT
Phaser accepting requests since Mon 01 Aug 2011 04:08:17 PM PDT
accepting requests since Tue 02 Aug 2011 09:22:34 AM PDT
xerox accepting requests since Thu 28 Apr 2011 11:45:37 AM PDT
3. Some applications recognize the printers and can print just fine
. (See item #2 in my initial posting, above.)
4. Some applications recognize none of the printers, and therefore, cannot print at all
. (See item #1 in my initial posting, above.)
Because of this divergence, it appears that there are two mechanisms for accessing the printers, and some class of the applications aren't using a working mechanism or the other mechanism broke.