The only reason that exclusivity contracts, like the one that Apple and AT&T have, is only an issue because all cellular providers are not all using the same technology. If these companies want to get more customers, then we need a standard that all cellular providers use. Since these companies use public airspace to conduct their business, then it is the people's right to demand this.
CDMA, while is does have its advantages, it lacking when you look at GSM. Verizon is certainly trying to assist world travelers, by offering phones with GSM radios, but this is not sufficient. Even if there needs to be a new standard engineered, it would be nice to see the playing field leveled for customers.
I am not going to list the differences between GSM(TDMA) or CDMA, but this information can be found in many places on the internet. Of course, 3G AT&T phones, Verizon, and Sprint phones do have one thing in common(at the very least): Qualcomm is getting rich off of all of them. AT&T's UMTS uses W-CDMA, Verizon is going to use UMTS for their 4G service, but I believe Sprint is going to use WiMax for their 4G.
I do not believe in stifling innovation, but I believe that most customers want to be able to purchase any phone that exist and use it with whatever carrier that choose. Carriers should be able to sell any phone that exist as well. If carriers want to offer a new technology, then it should be able to work with at least one or two previous technologies to ensure proper coverage for customers.
Proprietary hardware looks good for those that are getting rich off of it, but it sucks for the end-user and many in the tech field. There is a reason why Windows-based PCs are so popular and why the old proprietary PC market died(hello Tandy and old IBM). People want choice; they always have wanted a choice. While it would be unreasonable to believe we can ever create something that will not be locked out of all future-available markets, we should strive to make products that work in all current markets/carriers(within financial reason). This will only occur when we have a proper standard.