> 	2.c) implement CUPS-side job preview if at all 
> possible. If not, emulate as done in one highly polished , 
> CUPS-loving/owning commercial platform.

Following a request I made in 2003, CUPS will finally provide
a mechanism to request print job file. See
http://www.cups.org/str.php?L118
Unfortunately, it seems to be planned for 1.4 release.

Michael.