We were going to write a section about mobile phones, but the found that somebody else already has.
Activists, rights defenders, and journalists use mobile devices and communications for reporting, organizing, mobilizing, and documenting. Mobiles provide countless benefits -- relatively low cost, increased efficiencies, vast reach -- but they also present specific risks to rights defenders and activists.
Additionally, information about other mobile uses, such as your photos or video, your data, the Internet sites you visit from your phone, and your physical location, are stored on your device and often logged by your mobile network. (The above graphic shows a schematic overview of the layers of the mobile networks to give you sense of the different elements that make up communications between two phones.) How much is this putting you at risk? This Overview will help you evaluate your level of risk in regard to your mobile communications.
Part I describes security vulnerabilities associated with mobile phone technology and the risks they pose to you - the information held by your mobile network operator (MNO or operator), the information stored on your phone, and the risks related to unauthorized use.
Part II discusses common phone capabilities - voice, SMS/text messaging, web browsing, mobile email, mobile photos and video, and smartphone apps. We describe the safety risks these pose for you and give you tips on how to minimize them.
Read the full article, Mobile security risks: A primer for activists, journalists and rights defenders from MobileActive.org. The section above is published under the (CC) BY-NC-ND license.
Free Your Android!
Android is a mostly free operating system mainly developed by Google. Unfortunately, the drivers for most devices and most applications from the "market" are not free (as in free speech, not free beer). They frequently work against the interest of the users, spy on them and sometimes can not even be removed. The Free Software Foundation Europe have got some really useful information on how to install free software on to your phone.
Apps for smartphones
The Guardian Project make security apps for Android smart phones for browsing the web securely, encrypting SMS/text messages, an more. They also recommend apps made by others.
The FDroid Repository is a 'market place' for free (as in freedom) apps for Android phones.
Text Secure is a way of using Off the record encryption with SMS messages on Android phones.
Anything on iPhones?