[Asbjørn Ulsberg]

I have the same problem and overwriting db-mysqli.php with db.php didn’t help. Just for completeness, here’s the error messages I encounter:

Warning: mysql_get_server_info() [function.mysql-get-server-info]: Can't connect to local MySQL server through socket '/var/run/mysqld/mysqld.sock' (2) in /home/<snip>/bbpress/bb-includes/db-mysqli.php on line 73

I suspect bbPress of having hard coded a connection to localhost and thus configuring define('BBDB_HOST', '...') to be something else than localhost doesn’t really matter. I don’t have MySQL and Apache installed on the same physical server, so I have to access MySQL through a hostname and thus localhost won’t work.