For those that use iWork on a computer, save to DropBox, and also edit iWork files on an iDevice that you open from DropBox, DB won't sync from the iDevice on its own. You can open the file in iWork from DB on the iDevice and edit (or create a new one) but it doesn't save changes to DB since iOS stores files the way it wants to, in the app data, it won't save back to DB on its own.
You need to get DropDAV from http://dropdav.com/
In iWork it doesn't give a save to DB option but it gives an option to save to a WebDAV server. You can link the dropdav account to DB and save to DB from there though. The server is the middle man to send it to DB. It uploads to the server then down to DB.
They have a 14 day trial, and if you want to keep using it it's $5 a month. DB has a 300M limit on the size of file you can transfer via WebDAV.