The old AT&T Wireless had free incoming texts (before they were bought by Cingular) which is part of the reason I never migrated over to Cingular. And IM apps on the iPhone like beejive, IM+, palringo, AIM, etc, all use data to send the IM's not texts, so you won't get charged for those. The only time you'd get charged a text, like people mentioned above, is if you were signed out of the AIM servers and you still have your screen name set to forward to your cell phone, then it forwards the IM's as texts since you're not actually logged onto the AIM server. But all the apps use data, so you don't have to worry there.