pSQL auth

Hello.

I noticed you are the maintainer of the TODO list for PostgreSQL.

I am an enthusiastic user of PostgreSQL, and I feel that with little effort
we could add pam authentication functionality. What do you think?
"Pluggable Authentication Modules" are well supported on many architectures,
eg. Linux or BSD or Solaris, users could authenticate in tens of ways.
The db administrator's will have choice of thousands of authentication
methods, e.g. Kerberos, standard Unix UID (/etc/passwd), SMB, NT Domain,
etc. etc.
I am looking forward for a NT Domain authentication for PostgreSQL, but
others could use one the thousands pam provide.

And also you will not have to mantain any more an "authentication tree" on
the PostgreSQL source code. You just delegate to pam libraries.

Thanks for evaluating my proposal,
Jacopo Silva