JDBC "User authentication failed"

Every time I try to connect to a postgresql database via JDBC I get a
"java.sql.Exception: User authentication failed"

I have configured pg_hba.conf as follows:

host all 127.0.0.1 255.255.255.255 trust

I have also tried:

host all 127.0.0.1 255.255.255.255 password passwd

after creating a new user and specifying their password in $PGDATA/passwd

The postmaster is running with the -i option, and I know that it is
listening to the port because I can see the "User Authentication Failed"
message pop up in nohup.out (where the output from postmaster/nohup is piped).

Anybody have an idea of what I am doing wrong? Any help would be appreciated.

thx.
-=Chris