WD seems to offer 3years
edit. this is from WD website. its the same for all drives. i think. i looked at a couple.
Western Digital has adopted a new warranty policy effective October 1, 2002. Western Digital WD Caviar Special Edition hard drives are covered under warranty for a three-year period. All other Western Digital products will be covered under a standard warranty for a period of one year. Products purchased before October 1, 2002 are covered under the product's original warranty, unless otherwise noted on the retail packaging.