I saw no errors, and when I run "yum list installed" I see the packages. The problem is, my customers' programs can't find netPBM and neither can I.
The netpbm packages contain a number of individual binaries, though none of them is named netPBM or netpbm. run the following commands to see for yourself
rpm -ql netpbm-progs | less rpm -ql netpbm | less