XBGMER and zerodog,
No, if the iPhone is connected via WIFI then there's no data usage via AT&T's network so in other word, it's free. Right now FaceTime is limited to WIFI only in 2010 and iPhone 4 to iPhone 4 only. in 2011, FaceTime may be allowed to go over cellular network, that's because not all network are ready for it (not just AT&T).
So if you have WIFI at home, use it! if you are at one of hotspot, use it! I always take advantage of WIFI hotspots and use cellular when outside of WIFI range so that way we don't go over the limit. That's why we consumed less data bandwidth due to WIFI and that's why many customers complained paying too much for "unlimited" when they used less so they want to pay less so AT&T change the Data rate.
If one use WIFI often, then use 200mb plan if use 50/50 then go for 2GB plan not expensive.
Text messaging is still unlimited if on TAP plan for new customers.
