I too thought so, but the following Seagate page says 2 years for external ones!:S Seagate External Desktop / Portable Storage Drive FAQs
But my recently bought internal one's warranty when checked is shown as 3 years.
Few Seagate freeagent models & Enterprise products carrys 5 year warranty 'as marked on the product itself. All other products sold from APRIL 2010 in Asia will only carry 3 years warranty , not applicable to OEMS !!