if you get this error or something simular when installing metasploit on kali this is what you need to do
error:

Setting up metasploit (4.5.3-2013032701-1kali0) ...
psql: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
Creating metasploit database user 'msf3'...
createuser: could not connect to database postgres: could not connect to server: No such file or directory
Is the server running locally and accepting
connections on Unix domain socket "/var/run/postgresql/.s.PGSQL.5432"?
dpkg: error processing metasploit (--configure):
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
metasploit
E: Sub-process /usr/bin/dpkg returned an error code (1)

solution:

gedit /etc/postgresql/9.1/main/postgresql.conf

and change the #listen_addresses = ‘localhost’
and port = 5433 to
listen_addresses = ‘localhost’
and port to 5432
then

service postgresql restart

apt-get remove metasploit && apt-get autoclean
apt-get install metasploit
and it should work just fin.
if any error put it in the comments below.