Carrier IQ seems to log information on both iOS and Android phones, over 3G or Wi-Fi, but only on Android the service violates privacy laws by using a bit of software, IQRD:
After connecting his HTC device to his computer, Trevor found that IQRD is secretly logging every single button that he taps on the phone–even on the touchscreen number pad. IQRD is also shown to be logging text messages.
There doesn’t seem to be a known way to turn this off on the Android OS. Nilay Patel from The Verge suspects that it is the carriers who are mainly responsible for having the software on the phone in the first place.