Wordpress should probably be upgraded to address security
vulnerabilities in version 2.8.6.  This includes at least one SQL
injection for authors
(http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=605603), some XSS vulnerabilities, and I think some others.

The full list of vulnerabilities can probably be obtained through
wordpress's release notes at

http://codex.wordpress.org/Version_2.9
http://codex.wordpress.org/Version_2.9.1
http://codex.wordpress.org/Version_2.9.2
http://codex.wordpress.org/Version_3.0
http://codex.wordpress.org/Version_3.0.1
http://codex.wordpress.org/Version_3.0.2
http://codex.wordpress.org/Version_3.0.3

Unfortunately, upstream isn't too great about publishing detailed
reports of their security issues.

This might also be a good time to talk to the wordpress-mu maintainer
about getting rid of the wordpress-mu package and working together on
3.x, now that wordpress and wordpress-mu have been merged.