concatenation with a null column (using ||) nulls the result?

inventory=> SELECT cabinets_name, cabinets_description 
FROM cabinets WHERE cabinets_datacenters = 2;cabinets_name | cabinets_description
---------------+----------------------548-4th-Cab2  |548-4th-RR1   |548-4th-RR2   |548-4th-Cab1  |
(4 rows)

inventory=> SELECT cabinets_name || ' - ' || cabinets_description AS concat 
FROM cabinets WHERE cabinets_datacenters = 2;    concat
-----------------


548-4th-Cab1 -
(4 rows)

Note: The cabinets_description for the "548-4th-Cab1" row is " ", 
not NULL, hence it being displayed. Is this standard SQL behavior? 

Client is from rpm: postgresql-8.0.7-1.FC4.1
Server is from rpm: postgresql-server-8.0.7-1.FC4.1

-neil