New Zenmap adds feature that does topology mapping

Zenmap is a GUI front end for nmap, the popular network and port scanning tool by fyodor.

Introduction
Zenmap is the official graphical user interface (GUI) for the Nmap Security Scanner. It is a multi-platform, free and open-source application designed to make Nmap easy for beginners to use while providing advanced features for experienced Nmap users. Frequently used scans can be saved as profiles to make them easy to run repeatedly. A command creator allows interactive creation of Nmap command lines. Scan results can be saved and viewed later. Saved scans can be compared with one another to see how they differ. The results of recent scans are stored in a searchable database. A typical Zenmap screen shot is shown in Figure 12.1. See the official Zenmap web page for more screen shots.

RadialNet-like

Seems very similar to what RadialNet does.