Not terribly fragmented but certainly not unified. Here's even better data http://www.marco.org/2011/11/30/more-ios-device-and-os-version-stats-from-instapaper

Not terribly fragmented but certainly not unified. Here's even better data http://www.marco.org/2011/11/30/more-ios-device-and-os-version-stats-from-instapaper http://www.marco.org/2011/11/30/more-ios-device-and-os-versi...