According to Pew's report, 54% of cell phone users in the U.S. have decided not to install an app once they discovered how much of their personal information it would access. (The amount of sensitive info an app can access typically is indicated by the "permissions" the app requests, listed on its information page.)
Also, nearly one-third of mobile app users report uninstalling an app from their phone because they learned it was collecting personal information they didn't wish to share. People from the lowest-income households (earning $30,000 or less per year) and men across all demographics were most likely to report taking this step.
But many mobile-privacy concerns stem not from the apps you download, but from what can happen with a device that can divulge so much sensitive information once it's out of your hands -- especially when it's in someone else's hands. Most cell phone users are somewhat aware of mobile privacy and many take at least some basic measures to protect it.
According to Pew:
• 41% of cell phone owners back up at least the photos, contacts, and other files from their phone.
• 32% have cleared their phone's Web browsing or search history.
• 30% of all cell phone owners (and 60% of smartphone owners) say they back up the entire contents of their phone (apps, data, files, etc.)
• 19% (especially younger phone owners) have turned off their phone's location-tracking feature due to concerns that companies or other people might access that information.
Of course, regardless of whether you turn off location tracking on your phone, your wireless carrier knows (and keeps a record of) where your phone is at all times it's connected to the cell network. Carriers can surrender this information to law enforcement, and it's unclear what else they may be doing with this data.