CPAN installations don't directly allow for the change of the MIBDIRS environment variable specified in SNMP/Util-env.pm. Installations on RHES5 Beta 2 and probably most others do not have a default location of /usr/local/lib/share/snmp/mibs. This means that the default "make test" will fail looking for the MIBs.
If the following change is made to SNMP/Util-env.pm, most user modification will probably be unnecessary. Since net-snmp-config is a prereq to the SNMP package which is a prereq to SNMP::Util, everything should work.
Change:
