Most likely you've got apache (or whatever web server you're running) set to support more children than you have postgresql set to support number of connections.
Generally speaking, pconnect is bad, and by the time you need it, you'll be solving a very real load problem.
Solutions:
Set apache to spawn fewer children / threads
Set PostgreSQL to support more connections
Stop using pconnect
Generally speaking, apache can run well for most small to medium sized audiences with 50 or so children.
Generally speaking, PostgreSQL can support up to about 500 connections on most modern hardware.
Generally speaking, pconnect is a solution in search of a non-existing problem.
There are exceptions to each of those generalizations.
