Nmap 5.50 is out, make sure to check it out. It contains a lot of new NSE stuff, including support for broadcast, pre- and post-rules and most of the scripts I, and many others, have created during the last year. For more information check out the official post http://seclists.org/nmap-hackers/2011/0
I’ve cleaned up the Nmap scripts page a bit to better reflect reality. Most of the scripts published on that page have been commited to the Nmap development release. I’m actively working on getting the remainder commited to. Once the scripts have been commited, they’re no longer maintained here. So, in order to try them out I recommend you to install the latest development release of Nmap. In order to do so, follow the steps outlined here.
I cleaned up and documented the script some more. The packets sent to the server over udp and tcp now both have NULL_AUTH credentials. The new version is available here.