
Verizon's new CDMA iPhone 4 appears to have an updated antenna system in place. Having a quick look at the phone, you'll notice there is a new top notch in the antenna that resembles the bottom notch on the current iPhone 4. According to Engadget:
Tim Cook has just confirmed on stage that changes had to be made to work on the CDMA network, meaning this is just an innocuous aesthetic alteration.
Source: Verizon's iPhone 4 has a CDMA-specific antenna, no other changes made -- Engadget