From the mailing list 'full-disclosure'.

GNessUs is a GPL fork of the Nessus security scanner. As a result of
recent announcements by Tenable, we believe a fork of Nessus is required
to allow future free development of this tool.

Whilst we would like to believe that we will be able to continue to take
updates of the Nessus 2 source code from the Nessus web site we will be
endeavoring to add fresh functionality and plugins as part of the GNessUs
project. The fork will be based on the current nessus 2.2.5 packages from
GNU/Debian, the source of which can be found above in a slightly modified
form. We would welcome contact from any interested developers.

This intention to fork has come after numerous pub and work discussions
between myself and colleagues of mine from within the UK security
industry.

Cheers,
Tim
- --
Tim Brown, GNessUs
<mailto:timb@gnessus.org>
<http://www.gnessus.org/>