Feature suggestion: Postgresql binding to one IP?

Hi people,

Is it possible for Postgresql to bind to one IP address? 

I'm trying to run multiple postgresql installations on one server.

The unix socket could be named accordingly:

Postgresql config bound to a particular port and all IPs.
.s.PGSQL.<portnumber> 

Postgresql config bound to a particular port and IP.
.s.PGSQL.<portnumber>.<ipaddress>

Any other suggestions/comments on running multiple instances of postgresql
are welcomed.

An less desirable alternative is to keep binding to all IP, use different
ports and name the ports, but specifying the port by name in -p doesn't work. 

Cheerio,
Link.