On handhelds themselves, there are some inherent privacy features that can help manage the influx of personal information. Featherman, for instance, points out that one of the biggest problems may simply be misplacing the device or having it stolen.
Information theft is also possible through the infrared port or a cable.
Doing so can thwart information thieves. As for private information such as address book entries, some handhelds let individual entries be protected with a password. Featherman recommends this procedure. It won't prevent the data from being copied onto company servers, but it will at least limit any embarrassment or liability. Calif. The company's products help manage software and data on mobile platforms.