Push events to the web app isn't important to me. Syncronization with a web app every few minutes would work well, and you could login to push a button if you needed the changes pulled immediately.
That's the way i implemented it in an iphone app i recently made: a 'sync now' button to pull anything new and push any updates to the server. Works quite well - I recently deleted my app (iphone died) and reinstalled it, one 'sync now' later and all my data was back.
I'm a big fan of using dropbox like this, and am hoping to explore this approach in a lot of productivity apps i plan to make in the future. I like the idea that the user can 'see' their data in a readable format (json,csv,yaml - i still haven't decided which i prefer!) in their dropbox\apps\MyApp folder.
It's like icloud but you feel in control, rather than 'my data is out there somewhere but i can't see it'.
My users would not be this excited if a "sync now" button on the web needed to be pushed. The point of Dropbox integration is to upload photos without leaving Lightroom/Aperture/etc. and not having to install a plugin: http://pgunupudi.blogspot.com/2009/09/dropbox-support-for-ou...
