Nubuntu was last released as a beta on 12/17/2008 and it seems that there has been nothing new or updated since 2008
phlak is old and as such outdated. I don't even think it's supported anymore
knoppixstd is a std.
From their website: "it is a collection of hundreds if not thousands of open source security tools." The dev's don't even know what is on the distro apparently. The best news from the website for this year is a new hosting mirror. Prior to that 2feb2005: "new version of STD will be released by end Q1 2005"
Hope that helps.