BUG #2180: log_statement=mod does not work

The following bug has been logged online:

Bug reference:      2180
Logged by:          Gilles
Email address:      s_gilou@yahoo.com
PostgreSQL version: 8.1.0
Operating system:   Linux RedHat ES3
Description:        log_statement=mod does not work
Details:

When I configure in the file postgresql.conf:
log_statement=mod
I don't have the update, delete, insert queries logged like it says in the
documentation :
http://www.postgresql.org/docs/8.1/interactive/runtime-config-logging.html

Could you tell me, what I need to do to get these queries logged?

Thanks
Gilles