PostgreSQL Upgrade Procedure

I've had PG 9.0 installed and working fine however it's Friday and I'm
running updates on the server & see that 9.1 is available. I know when
I upgrade, I will now have two instances of PostgreSQL installed under
/etc/postgresql:

Code:

slave:~# cd /etc/postgresql
slave:/etc/postgresql# ls -l
total 8
drwxr-xr-x 3 postgres postgres 4096 Aug 31 13:02 9.0
drwxr-xr-x 3 postgres postgres 4096 Sep 9 10:08 9.1

EndCode:

My question is what is the official procedure for removing the old
version and then running 9.1 only on my system. I don't want to leave
9.0 config files or directories so can someone please point me into
the clean and correct way of properly upgrading from 9.0 to 9.1? I did
do a pg_dump on my two databases & the default 'postgres' database and
backed them up so I can import them into the new 9.1 instance.