Nmap 5.0 Released - Biggest Release Since 1997

Nmap 5.0 was released on July 17th 2009 and according to the official announcement, this is the biggest release since 1997.

Nmap (or Network Mapper) is a powerful, complete, open-source tool for network exploration and port scanning.

This release features many improvements, among which are the new Ncat tool for data transfer, redirection and debugging; the Ndiff scan comparison tool which reports changes between different network scans; the performance improved dramatically; the Nmap Scripting Engine allows users to write scripts to automate a wide variety of networking tasks. See the users' changelog here.