You may well read today about how "Carrier IQ" spy software has been discovered in Apple's iPhones and iPads. The situation isn't nearly as bad as it might sound, but it never hurts to revisit your phone's privacy configuration.
On most Android, Nokia and BlackBerry devices, Carrier IQ re-transmits a wealth of data, including your web searches and traffic, keystrokes, texts, and GPS location. On the iPhone and iPad, the situation is not nearly so dire. On Apple devices, Carrier IQ only reports your exact location and whether you're making a phone call - information your carrier already has in less precise form - and even then only does so if you've enabled certain settings.
To check your settings under the latest iOS, open the "Settings" app, then select "About" at the top, then scroll way down, then select "Diagnostics & Usage." If "Automatically Send" is checked, your iPhone may sometimes transmit your exact location and whether you're on a phone call to your carrier, depending on whether you have "Location Services" enabled. If you're not comfortable with this, select "Don't Send," which stops all use of Carrier IQ. Just keep in mind that your carrier can still stalk you pretty closely; they know what cell twoers you connect to. And they know where you live! (Cue shockhorror!)