  AT&T Users Switching to Verizon  A new survey from ChangeWave
takes a closer look at how the Verizon iPhone may shake up the
mobile market, revealing the highest churn rate AT&T has seen
since ChangeWave began surveying mobile subscribers. A total of
4,050 subscribers were surveyed, with 15% of AT&T and T-Mobile
users saying they were likely to switch carriers in the next 90
days, compared to only 4% from Verizon.  Diving even deeper with
AT&T specifically, things don't look much better. The survey was
conducted before the Verizon iPhone was officially announced,
but still shows 16% of AT&T subscribers were looking to jump
ship to Verizon once they have the iPhone. Another 23% said they
weren't sure, but could possibly make the switch. But when they
looked at AT&T iPhone users only, they found as high as one-in-
four (26%) were likely to leave AT&T for Verizon.  This somewhat
falls in line with our own poll showing 41% of readers would be
sticking with AT&T, while 15% were willing to switch for the
Verizon i