Canon Knowledge Base - Replacing the Date Battery for the PowerShot SX1 IS, SX10 IS and SX20 IS.
Amazon.com : Canon Powershot SX20 IS Digital Camera Battery Charger Replacement Charger for AA and AAA Battery - 110/220V Includes a EU Adapter : Camera And Camcorder Battery Chargers : Electronics
Canon announces PowerShot SX20 IS super-zoom: Digital Photography Review