As it is today, Vodafone (which owns 45% of Verizon Wireless) uses GSM technologies and the current GSM-based 3G technology HSPA. GSM is used in the U.S. by AT&T and T-Mobile, among others. Verizon Wireless's network uses CDMA technology, which was developed by Qualcomm, and is incompatible with GSM/HSPA. LTE will be the next generation, or 4G, technology, used by Vodafone and many network operators worldwide. It was expected that Verizon Wireless would choose the CDMA-based equivalent of LTE, which is UMB, or EV-DO Rev. C technology. (Are you confused by the alphabet soup of acronyms yet???)
The two CEOs cited the desire to allow their customers to roam freely between networks as one reason for choosing the LTE path together. While this certainly makes sense in the long run, it signals dark days ahead for the future of CDMA and its supporters, such as Qualcomm and Sprint.
Neither Qualcomm, nor the CDMA Development Group commented on the matter, but you can be sure we'll hear from them eventually if Verizon Wireless does indeed choose LTE rather than UMB for its next-generation network.
Sarin and Seidenberg also noted that the companies will likely trial WiMax networks as well.