Some of the highlights are:
o [NSE] Added more scripts, bringing the total to 131!
o Performed a major OS detection integration run.
o Performed a large version detection integration run.
o [Zenmap] Added the ability to print Nmap output to a printer.
o [Nmap, Ncat, Nping] The default unit for time specifications is now
seconds, not milliseconds, and times may have a decimal point.
o Ports are now considered open during a SYN scan if a SYN packet
(without the ACK flag) is received in response.
o [Ncat] In listen mode, the --exec and --sh-exec options now accept a
single connection and then exit, just like in normal listen mode.
o UDP payloads are now stored in an external data file, nmap-payloads,
instead of being hard-coded in the executable.
o Added a new library, libnetutil, which contains about 2,700 lines of
networking related code which is now shared between Nmap and Nping
o Improved service detection match lines.
o Improved our brute force password guessing list by mixing in some
data sent in by Solar Designer of John the Ripper fame.
o [Zenmap] IP addresses are now sorted by octet rather than their
string representation.
o [Ncat] When receiving a connection/datagram in listen mode, Ncat now
prints the connecting source port along with the IP address.
o Added EPROTO to the list of known error codes in service scan.
o Updated IANA IP address space assignment list for random IP (-iR)
generation.
o Zenmap's "slow comprehensive scan profile" has been modified to use
the best 7-probe host discovery combination we were able to find in
extensive empirical testing
o Zenmap now lets you save scan results in normal Nmap text output
format or (as before) as XML.
o [NSE] Raw packet sending at the IP layer is now supported, in
addition to the existing Ethernet sending functionality.
o Nmap now honors routing table entries that override interface
addresses and netmasks.
o [Ncat] The HTTP proxy server now accepts client connections over
SSL, and added support for HTTP digest authentication of proxies, as
both client and server.
o Improved the MIT Kerberos version detection signatures.
Plus many bugfixes and improvements.
For full changelog, see http://nmap.org/changelog.html