I am running my development on Ubuntu 11.10, and RubyMine
Here is my development settings for the database.yml: which RubyMine created for me
develop
You can go to your /var/lib/pgsql/data/pg_hba.conf file and add trust in place of Ident It worked for me.
local all all trust host all 127.0.0.1/32 trust
For further details refer to this issue Ident authentication failed for user