Something end users probably don't realize is that Office isn't just a suite of applications, but also a platform for development.
The idea behind building apps on top of Office is that you can provide users with apps in an environment with which they're already familiar and comfortable. Some of the plumbing is also already taken care of for devs, so you can rely on the strength of the
platform rather than start entirely from scratch to build your apps.
To help devs get started, there are some reference apps that have been released.
Today, they're pushing out a reference app to show how OBAs can be used in the medical industry.
If you have users who prefer to work inside Office apps rather than leaving the familiar environment for an app built from the ground up, then you'll find this interview interesting...
(Thanks to Tim Sneath
for lending us his office without his permission. Asking to use it would have resulted in all kinds of wasted time, so bypassing that step was a great convenience for us.)