Touch 1Gen
http://pfd.apple.com/ProtectedAsset/iPodTouch/061-7161.20090909.VbuyJ/iPod1,1_3.1.1_7C145_Restore.ipsw?downloadKey=1252609653_8baad250300fd5d4c9bb647c27721173
Touch 2Gen
http://pfd.apple.com/ProtectedAsset/iPodTouch/061-7162.20090909.NkUy7/iPod2,1_3.1.1_7C145_Restore.ipsw?downloadKey=1252609653_632e8b2787b378c83c63a12367e9684b
Touch 3Gen
http://appldnld.apple.com.edgesuite.net/content.info.apple.com/iPod/SBML/osx/bundles/061-7163.20090909.NtstR/iPod3,1_3.1.1_7C145_Restore.ipsw
Continue reading iPhone/iPod Touch Firmware3.1