The version history of iPhone OS Firmware begins with the release of the iPhone on June 29, 2007. Apple provides updates to the iPhone’s and iPod Touch’s operating system through iTunes, similar to the way that other iPods are updated.The iPhone 3G was released  on July 11, 2008 and supported faster 3G data speeds and Assisted GPS.Here we have the complete list of
iPhone Firmware released till january’09 . This the must bookmarked collection for frequent
iPhone Upgrader & downgrader.We have links of both
iPhone 2G &
iPhone 3G.

Download Links for 
iPhone 1st Gen firmware:

iPhone firmware v1.0    
iPhone firmware v1.0.1
iPhone firmware v1.0.2
iPhone firmware v1.1.1
iPhone firmware v1.1.2
iPhone firmware v1.1.3
iPhone firmware v1.1.4
iPhone firmware v2.0
iPhone firmware v2.0.1
iPhone firmware v2.0.2
iPhone firmware v2.1
iPhone firmware v2.2
iPhone firmware v2.2.1

 Download Links for 
iPhone 3G  firmware :

iPhone 3G firmware v2.0
iPhone 3G firmware v2.0.1
iPhone 3G firmware v2.0.2
iPhone 3G firmware v2.1
iPhone 3G firmware v2.2
iPhone 3G firmware v2.2.1