Because phone and PDA data is stored in flash memory, it's retained even if the device's battery is drained or removed. To delete flash memory data, users have to do a "hard reset," which returns the hardware to a factory-fresh condition. Each phone and PDA maker uses a different hard reset procedure; some, in fact, can only be down by a technician or after contacting the phone service's help desk.
Phones and PDAs are not the only electronic gear which aren't properly wiped before they're tossed or sold. Studies of the contents of used hard drives have found similar results: a wealth of data, some of it personal or confidential.
Trust Digital recommended that users secure their cell phones and PDAs using passwords, to lock out casual snooping if the devices are lost.
[Note: This story was updated at 3:05 pm. Statement from Nick Magliato, chief executive of Trust Digital, replaced with quote from Trust Data chief technology officer Norm Laudermilch.]