Some details from the readme...

Verizon PN 820 AKU3.4.2 Maintenance Release
This software update makes available some new features and corrects some issues. Some of the primary enhancements are:
Upgraded OS to Windows Mobile 5.0 AKU 3.5.2.
Added the 2007 Daylight Saving Time Patch
Upgraded Voice Command application to version 1.6.
Enabled the Bluetooth Voice Command function.
Improvements to Battery Standby and Talk Time.
Set the default ring tone as “Verizon Ring”.
Fixed several Bluetooth issues with Motorola and Jabra headsets.
Added Power-Up and Power-Down tones.
Enabled capabilities to set saved pictures as wallpaper on the sub LCD.
Enabled capability to view music file played using media player on the sub-LCD, when the flip is closed.