When the iPhone's v.2 operating system was pitched with MS-Exchange support, one of the blessings touted at the release was the absence of per-user licensing fees for synch support software. To use corporate contacts, email, and calendar services offered by MS-Exchange, the RIMM Blackberry famously requires back-office support from proprietary servers whose license fees scale with the user population; Apple builds ActiveSync into iPhones' stock configuration. Cost isn't device price alone, apparently.
Between bottom-up pressure from users who are beginning to buy Apple's advertising that browsing is important on a smartphone, and the top-down cost pressure caused by Apple's competition, migrations to iPhone have begun in enterprise.
I wonder how far that might go.