Accessible Folder Tabs

Greetings,

Katie mentioned a document, "How to Implement Folder Tabs with Real HTML Text 
and Background images."  This interests me, as I had discounted using 
background images to convey information as unaccessible, because they can't 
carry alt or longdesc.  Can you share some more info about this technique?

Regards,
-- 
Thanasis Kinias
Vice President & Manager of Information Systems
Optimal LLC
Scottsdale, Arizona, USA