[* black] Like the iPhone 3G and 3GS, there are two silver [product|145006|Phillips #00] screws at the bottom of the phone.
[* black] In a departure from the design of the 3G and 3GS, removing the screws releases the rear case, not the front glass.
[* black] This design makes switching out the rear panel trivial, but unfortunately means that [link|http://www.ifixit.com/Guide/Repair/Installing-iPhone-4-Front-Panel-Assembly/3148/1|replacinglink|http://www.ifixit.com/Guide/Device/iPhone_4|replacing the iPhone 4 front panel] will likely be rather challenging.
[* black] This design makes switching out the rear panel trivial, but unfortunately means that [link|http://www.ifixit.com/Guide/Repair/Installing-iPhone-4-Front-Panel-Assembly/3148/1|replacinglink|http://www.ifixit.com/Guide/Device/iPhone_4|replacing the iPhone 4 front panel] will likely be rather challenging.