This link is not completely correct however. Even though the link indicates you can ***xxx8226;NOT send or receive any information over the internet, in any way shape or form, despite what you heard about it being possible.**** It is in fact incorrect. On AT&T you can in fact do ALL the things it says you can not, WITHOUT a data plan. If you choose no data plan then you are assigned to the Pay Per Use Media Net plan @ a rate of .01 cents per kb. I use data routinely WITHOUT a data plan and have had no issues. I would not recommend it for data intensive users but for those who only get Google map directions or use the net infrequently, the PPU is fine.
These facts have been debated regularly, but I have the proof to back up my own experiences.
Of course as of Sept. 6th AT&T is requiring all "New Activations" and upgrades involving Smart Phones to have a data plan. They are grandfathering in existing smart phone users without data but if you ever need to replace your phone, even just straight across, it requires that "New Activiation". So as long as you are never in need of a contract renewal to get that subsidized phone your are golden...lol.