I have to update wordpress on all branches from 2.3.3 to 2.5.1. There
are security fixes in 2.5.1
http://wordpress.org/development/2008/04/wordpress-251/
and it is hard for me to tell if they really affect the 2.3.3 release or
not. As the 2.3.x branch is not continued anymore the only way to avoid
security bugs is to update to 2.5.1.
Adrian