Yes, there is free UMTS/HSPA/EDGE roaming on AT&T for post-paid plans (aka not the $30 100 minute/5gb plan) and there is a data limit. For my plan, its 50 megabytes, which doesn't seem like much, but AT&T throttles you to 128kbit/s, so you really have to work hard to get to that 50 megs.