Asymco's Horace Dediu offers an interesting analysis of new data on Verizon's smartphone device sales over the past year, concluding that, despite a growing Android platform, Verizon finds itself in a position in which it may have had little choice but to accept Apple's terms to bring the iPhone to the carrier.
Dediu's analysis is based on that fact that sales of Android and Windows Mobile smartphones at Verizon have grown only slightly faster than the rate at which sales of Research in Motion's BlackBerry and Palm's webOS devices have fallen so far in 2010, yielding an overall sales growth rate for Verizon far short of that seen with the iPhone on AT&T. But even Android by itself (and a small fraction of sales for Windows Mobile devices that can't be separated out from the Android data) isn't selling as well or growing nearly as quickly on Verizon as the iPhone is on AT&T.
In an apples-to-apples comparison, in Q3 the iPhone at AT&T outsold Android at Verizon (remember, same addressable market) by a factor of 2.5. This is with a variety of devices and vendors thrown in the market. We hardly ever get to see this finely grained a comparison when looking at platforms.