Get TikiWiki 2.4 here:
https://sourceforge.net/project/showfiles.php?group_id=64258&package_id=266122
More information on 2.0
http://doc.tikiwiki.org/TikiWiki+2.0
http://info.tikiwiki.org/art35
More information on 2.1
http://info.tikiwiki.org/art40
More information on 2.2
http://info.tikiwiki.org/art41
More information on 2.3
http://info.tikiwiki.org/art51
The security issue is addressed here:
http://secunia.com/advisories/34273/
As always, please report any security issues to security.tikiwiki.org
Work is ongoing on TikiWiki 3.0, which will be released in May 3rd, 2009. The main focus of version 3.0 will be further enhancements to the user interface, the admin interface, the theme system and built-in themes. Additional goodies include webservices and enhancements to the plugins.