I have whipped up a quick script some of you may find useful.
ip2mapplot.py is a Python script for resolving a number of IP addresses to latitude / longitude coordinates and plotting them on a world map
Below is an image generated from one days worth of Senderbase drops on our Ironport MGAs:
Source code is available here: http://research.mince.ac.nz/ip2mapplot.py
Further instructions here: http://insecure.io/index.php/Code/ip2mapplot