Those eager Verizon subscribers that pre-ordered the iPhone 4 are today starting to receive their smartphones. Not surprisingly, the ever-resourceful folks over at iFixit have already ripped open the iPhone 4 that they received today.

While there was some small changes visible from the outside that we already knew about (repositioned antenna gaps and hold/volume buttons), there's more going on underneath than just a switch from a GSM-based chipset to a CDMA-compatible one.

IFixit reports that Verizon's version of the iPhone 4 features the Qualcomm MDM6600 chip [datasheet], which is the exact same chip that is found in Motorola's Droid Pro world phone. That means that the chip not only supports CDMA2000, but it also supports HSPA+ which Apple conveniently disabled on this particular outing.

The folks at iFixit reckon that it was probably easier for Apple to simply go with a CDMA-only configuration now given the antenna constraints in the current iPhone 4 design. But future generation of the iPhone could very well support both CDMA and GSM which would simplify SKUs for Apple -- at least until LTE versions of the iPhone start rolling off the assembly line.