There are two way you can go about doing this :
SNMP : you can poll using the following OID (ipRouteMask) and get the answer :
snmpwalk -c public 172.16.100.20 .1.3.6.1.2.1.4.21.1.11
RFC1213-MIB::ipRouteMask.0.0.0.0 = IpAddress: 0.0.0.0
RFC1213-MIB::ipRouteMask.1.1.1.0 = IpAddress: 255.255.255.0
RFC1213-MIB::ipRouteMask.2.2.2.0 = IpAddress: 255.255.255.0
RFC1213-MIB::ipRouteMask.10.1.1.0 = IpAddress: 255.255.255.0
RFC1213-MIB::ipRouteMask.171.68.0.0 = IpAddress: 255.255.0.0
RFC1213-MIB::ipRouteMask.171.69.0.0 = IpAddress: 255.255.0.0
RFC1213-MIB::ipRouteMask.172.16.99.21 = IpAddress: 255.255.255.255
RFC1213-MIB::ipRouteMask.172.16.100.0 = IpAddress: 255.255.255.0
RFC1213-MIB::ipRouteMask.172.16.186.26 = IpAddress: 255.255.255.255
Using CW2000 : There is a utility call NetShow that can execute a particular IOS CLI command on a given # of managed devices. This comes in very handy for short and quick reports like this. You can include the IOS command like "show run | i address".
Hope this helps..