iphone 3GS
http://appldnld.apple.com/iPhone4/041-0549.20110325.ZxP8u/iPhone2,1_4.3.1_8G4_Restore.ipsw
iphone 4
http://appldnld.apple.com/iPhone4/041-0551.20110325.Aw2Dr/iPhone3,1_4.3.1_8G4_Restore.ipsw
ipad 1
http://appldnld.apple.com/iPhone4/041-0550.20110325.Zsw6y/iPad1,1_4.3.1_8G4_Restore.ipsw
ipad 2 wifi
http://appldnld.apple.com/iPhone4/041-0556.20110325.64rfg/iPad2,1_4.3.1_8G4_Restore.ipsw
ipad 2 3G
http://appldnld.apple.com/iPhone4/041-0557.20110325.Jy76y/iPad2,2_4.3.1_8G4_Restore.ipsw
ipod 4g
http://appldnld.apple.com/iPhone4/041-0545.20110325.We3Rt/iPod4,1_4.3.1_8G4_Restore.ipsw