Before iCloud hits, I decided to check out my data usage for the iPhone 4s in our family. We have two iPhones on AT&T, mine and my wife's. I'm on Wi-Fi usually, but I do travel a lot and stream a lot of music and podcasts. My wife is on Wi-Fi most of the time too, but, my daughter tends to use the Netflix app way more than we probably should allow. I'm not sure exactly what, but something started spiking our data in August & September. We aren't using iOS 5, so I'm not sure what it could be. Anybody else seeing this trend? If you want to take a look at yours, login to your wireless account and you should be able to get similar graphs.
Wife's Data Usage (Top) My Data Usage (Bottom)