I've used an iPod Touch for years and finally got the new iPhone 4S through AT&T with the 200MB plan. Because I know there is not a lot of data available in this plan, I want to be careful and not to go over. I'm wondering if you guys have any tips on keeping the data down. I'm wondering if things like push notifications and some background apps use a lot of data. Also wondering if apps Siri and GPS use a lot of data. Thanks!