cd /home/damien/
wget http://wwwmaster.postgresql.org/redir/357/f/source/v9.0beta3/postgresql-9.0beta3.tar.gz
tar xzvf postgresql-9.0beta3.tar.gz 
cd postgresql-9.0beta3/
./configure 
make

sudo /etc/init.d/postgresql-9.0 stop
sudo cp -pr /usr/local/pgsql/bin/ /usr/local/pgsql/bin-9.0beta3/
sudo make install

sudo /etc/init.d/postgresql-9.0 stop

FAIL !

FATAL:  database files are incompatible with server
DETAIL:  The database cluster was initialized with CATALOG_VERSION_NO 201004261, but the server was compiled with CATALOG_VERSION_NO 201008051.

cd ~/postgresql-9.0.2/contrib/pg_upgrade
make
sudo make install
cd ../pg_upgrade_support/
make
sudo make install

sudo su - postgres
cd /var/lib/postgresql/
mv 9.0 9.0-beta3
mkdir 9.0
/usr/local/pgsql/bin/initdb -D /var/lib/postgresql/9.0/

/usr/local/pgsql/bin/pg_upgrade --old-datadir=/var/lib/postgresql/9.0-beta3/ --new-datadir=/var/lib/postgresql/9.0 --old-bindir=/usr/local/pgsql/bin-9.0beta3/ --new-bindir=/usr/local/pgsql/bin/ --old-port=543300 --new-port=543400