colleague recently asked how could they publish from Apple Pages on an iPad to Dropbox. Turns out the solution is pretty easy and actually opens up additional ways to share files.
1. Open the desired file and tap the tools button (wrench).
2. Choose Share and Print.
3. Choose Open in Another App.
4. Choose a File format.
5. Choose from a list of compatible apps.
The same general method also works in Apple Numbers and Keynote.