AT&T has delivered contradictory statements regarding the future of the 250MB for $15 iPad with Wi-Fi + 3G data plan to separate publications. Speaking with Chicago Now, AT&T spokesman Mark Siegel said that users currently on the $30 a month unlimited iPad plan would be able to keep it, while users who haven’t signed up for it will be unable to, and will need to choose from the DataPlus plan, which offers 200MB for a $15 charge, or the…