AT&T today announced that it plans to add 2GB of data usage to its smartphone tethering plan. According to the release, current tethering customers will automatically get the additional 2GB of monthly data usage added to their plans at no extra charge as of February 13; customers who sign up for tethering afterwards will get the additional data from the start of their tethering plan. The total cost for 4GB of data plus tethering capability will be $45 per month, the same price iPhone users paid for 2GB of data plus tethering in the past; users who exceed their data limits will be charged an overage fee of $10 per gigabyte. The change coincides with the release of an “AT&T Mobile Hotspot” app and the launch of the HTC Inspire 4G, however, the announcement makes no mention of whether a similar app will be offered for iPhone users, or if the company plans to make use of iOS 4.3’s Personal Hotspot feature. Notably, Verizon Wireless has said that it will also charge $20 for use of the iPhone’s Personal Hotspot feature, but the 2GB of data included in the Verizon plan is for Personal Hotspot use only, while AT&T’s extra data will be applied to collective use across all devices.