Just saw this on the Cruise West web site:

Single Supplement
For any 2010 voyage, travel in a cabin by yourself at the same per person price as passengers who are sharing a cabin.

Offer is capacity controlled, available on select 2010 sailings, and subject to change without notice. Restrictions apply. Call for details and availability. This offer is not combinable with group rates.

Cruise West Web Site: Cruise West small ship cruises – Alaska cruises, Mexico, Costa Rica & more