"July 16, 2009 -- Insecure.Org is pleased to announce the immediate, free availability of the Nmap Security Scanner version 5.00 from http://nmap.org/. This is the first stable release since 4.76 (last September), and the first major release since the 4.50 release in 2007. Dozens of development releases led up to this.
Considering all the changes, we consider this the most important Nmap release since 1997, and we recommend that all current users upgrade."
Download Nmap 5.00:
Ed Skoudis' Initial Impression of 5.00: