firmware version. Please note that if you use Safari you Below you can find the direct connections to the iPhone Firmware Files for every issued should disable the auto unzip feature. It may be simpler to just use Firefox!

1.0.0: iPhone1,1_1.0_1A543a_Restore.ipsw
1.0.1: iPhone1,1_1.0.1_1C25_Restore.ipsw
1.0.2: iPhone1,1_1.0.2_1C28_Restore.ipsw
1.1.1: iPhone1,1_1.1.1_3A109a_Restore.ipsw
1.1.2: iPhone1,1_1.1.2_3B48b_Restore.ipsw
1.1.3: iPhone1,1_1.1.3_4A93_Restore.ipsw
1.1.4: iPhone1,1_1.1.4_4A102_Restore.ipsw
2.0.0 (2G): iPhone1,1_2.0_5A347_Restore.ipsw
2.0.0 (3G): iPhone1,2_2.0_5A347_Restore.ipsw
2.0.1 (2G): iPhone1,1_2.0.1_5B108_Restore.ipsw
2.0.1 (3G): iPhone1,2_2.0.1_5B108_Restore.ipsw
2.0.2 (2G): iPhone1,1_2.0.2_5C1_Restore.ipsw
2.0.2 (3G): iPhone1,2_2.0.2_5C1_Restore.ipsw
2.1.0 (2G): iPhone1,1_2.1_5F136_Restore.ipsw
2.1.0 (3G): iPhone1,2_2.1_5F136_Restore.ipsw
2.2.0 (2G): iPhone1,1_2.2_5G77_Restore.ipsw
2.2.0 (3G): iPhone1,2_2.2_5G77_Restore.ipsw
2.2.1 (2G): iPhone1,1_2.2.1_5H1_Restore.ipsw
2.2.1 (3G): iPhone1,2_2.2.1_5H11_Restore.ipsw
3.0.0 (2G): iPhone1,1_3.0_7A341_Restore.ipsw
3.0.0 (3G): iPhone1,2_3.0_7A341_Restore.ipsw
3.0.0 (3GS): iPhone2,1_3.0_7A341_Restore.ipsw


NOTE*: I will revise this as new firmware versions arrive out of course :)