I have Angry Birds both on my iPhone and iPad.
I find it frustating that I have reached far ahead on the iPhone, but on the iPad I am still in the early levels.
Is it possible to sync my progress between the two devices?
I agree with this question and have an unfortunate answer.
The saddest part of the iOS line is that iTunes does not back up CoreData / Application generated data (save games, favorites, you know, locally saved data). The only way this is feasible is if the application supported saving progress back to the server, and loading it back to the device next time you play. And, clearly, Angry Birds doesn’t.
This is an opportunity to contact the developers about Angry Birds and ask them to implement a server-side store of your progress, in ADDITION to the local data.
This answer is 50% wrong. A server side store would be great, and iTunes doesn’t back up Application generated data, but you CAN pull saved files out with some finagling.