temp tables ORACLE/PGSQL

Hi
I used to work with Oracle and now tryin' PostgreSQL I'm a bit
confused.
I found that creating temp table in one session does not  make it
available for other sessions for the same user? Is this intended??

I was tryin to use because of lack of session and package variables in
PGSQL (thats what I know).  But I'm not sure if I have to create  a
temp table at the beginning of each session? Or just like in Oracle
create temp table definition and all whats temporar is data.

If creating a temp table for each connection is a must then maybe You
can tell me if there is any triger /event  that is being called during
connecting to db. I guess that would be the best place to create temp
tables and feed it up with session parameters.
Regards 
fisher