I was expecting the Verizon iPhone teardown to reveal nothing. Literally a different chip for CDMA, some ASICs, a little antenna re-jiggering and that's it. Boy, was I wrong.
The latest modem chipsets that have been added to the Gobi product family deliver support for CDMA2000® 1xEV-DO Rev. A and Rev. B, HSPA+, dual-carrier HSPA+ and LTE with integrated backwards compatibility to HSPA and EV-DO.
This opens up an incredible amount of possibilities -- but let's not jump to conclusions. The Verizon iPhone 4 doesn't have a SIM slot so you can't activate it on a GSM carrier (like AT&T or T-Mobile) without some serious hacking.
Update: iFixIt hypothesizes that Apple didn't release the VeriPhone as a multi-band "world phone" because a CDMA-only phone supports two cellular frequency bands, while Apple supports five bands in the GSM version.
Apple hates multiple SKUs -- except when selling high-cap iOS devices -- and the MDM6600 is evidence of that. The inclusion of the Qualcomm chip is simply a preview of what's to come in the single-SKU iPhone 5 that we'll see this summer or fall.
Below is a full-size shot of the Verizon iPhone 4 main board, dozens more can be found at iFixit.