Getting PostGIS 1.5.3 working with Postgresql90 (Macports)

What I want to do is import some shape files, using the shp2pgsql loader. However, I need a database first, and I've read I need to make it spatially aware, which means creating it from the "template_postgis". All the docs I read indicate that template_postgis should be present after installing PostGIS. But… When I try to create a database from that template, I'm told it's missing.

> createdb -T template_postgis demo -U postgres

createdb: database creation failed: ERROR: template database "template_postgis" does not exist

I've found tutorials on creating your own postgis template ( http://www.lincolnritter.com/blog/2007/12/04/installing-postgresql-postgis-and-more-on-os-x-leopard/ ), but I'd like to use what appears to be the standard one. Actually, I wondered if PostGIS was even running (Macports indicates it's installed and active):

> sudo port installed | grep postg

postgis @1.5.3_0+postgresql90 (active)
postgresql90 @9.0.5_0 (active)
postgresql90-server @9.0.5_0 (active)
postgresql_select @0.1_0 (active)

I tried importing a SHP file anyway:

> shp2pgsql -c -D -s 4269 -i -I demo.shp | psql -d demo -U postgres

Shapefile type: Arc
Postgis type: MULTILINESTRING[2]
SET
SET
BEGIN
NOTICE: CREATE TABLE will create implicit sequence "nrn_ab_8_0_roadseg_gid_seq" for serial column "nrn_ab_8_0_roadseg.gid"
NOTICE: CREATE TABLE / PRIMARY KEY will create implicit index "nrn_ab_8_0_roadseg_pkey" for table "nrn_ab_8_0_roadseg"
CREATE TABLE
ERROR: function addgeometrycolumn(unknown, unknown, unknown, unknown, unknown, integer) does not exist
LINE 1: SELECT AddGeometryColumn('','nrn_ab_8_0_roadseg','the_geom',...
^
HINT: No function matches the given name and argument types. You might need to add explicit type casts.
ERROR: current transaction is aborted, commands ignored until end of transaction block

Appears as though Postgis isn't even 'there'.
(Sorry, I'm a MySQL guy. I'm just trying to get started without asking too many dumb questions.)

Best regards,
René Fournier