The Droid is more than capable of replacing other handhelds. First off, the Droid is very easy to use. The applications have a consistent UI which makes learning new applications simple. Installing and updating applications via the Android Market is a snap. Desktop syncing is a bit of a challenge, since there isn't a desktop sync program, but all activity occurs wirelessly and most consumers will be happy with this slick little phone.
Applications on Android have a very modular architecture; each is, by default, independent of all other applications. Android is Linux-based and inherits the Unix userID model. Each Android application runs under its own userID and launches a new JVM under a new process. If one Android application crashes, it shouldn't affect other applications at all. By the same token, Android applications don't share data or libraries, other than those supplied by Android. The SDK has functions that allow for interprocess communications as designated by the application developer. If you are going to be supporting Android phones, and it's a good bet that you will be, it's worth getting an overview of Android's application framework.
The Android operating system has a fairly robust permissions system but the platform isn't fully open, which hobbles what you can do centrally. For example, the enterprise can't control whether users install applications and can't stop users from uninstalling applications. It would be nice for an enterprise to be able to add programs for device management or enterprise applications and ensure that users couldn't uninstall them. The Android OS, which is a custom Linux distribution, has the capability to segregate applications at the file system and process level, and it is capable of having applications installed that the user can access but not delete.
Verizon's Droid has a number of pre-installed applications like a Facebook client and Visual Voicemail that can't be removed by the phone's owner. Right now, there is no way for enterprise IT to deploy similarly protected applications but it's coming. A Google Spokesperson said:
"Future versions of Android will introduce more functionality for IT managers to deploy enterprise devices, which will be of particular interest to our Google Apps customers. Consumer software is driving forward innovation in business, and we look forward to bringing the benefits of Android to more people at work, but we don't have any specifics to announce at this time."