I just got off the phone with ATT.
Anyone that joined ATT yesturday Monday, June 07, 2010 there is no more unlimited plan there will be a 2GB $25 plan and or a 250MB $10-15 plan. If you pass the limit they will charge you a fee of $10 for every time that you pass the limit of 2GB and or 250MB. If you are an existing customer of ATT meaning before Monday, June 07, 2010 you will be able to keep the unlimited data plan.
Anyone that has an iPhone now do NOT sell your iPhone if you do the unlimited plan will be dropped and you be forced stick with the 2GB data plan. The only you can keep is if you keep your iPhone which you have now and save your money till the date is comes out and then activate the new iPhone 4G. Do to this I took my iPhone off from eBay because I do want my unlimited data plan, because I don't work well with keeping up with my internet usage.