Back in January, a new “PAD_CASE_LOCK” feature was discovered in the beta version of iOS 4.3, and explained as a way to “Automatically lock and unlock your iPad when you close and open the iPad cover.” Since the first-generation iPad doesn’t have any hardware that would enable this feature, we wondered whether the next iPad would gain a proximity sensor or some other trick (such as a near-field communication chip) to make it possible.

According to a well-informed source, hardware support for the feature is apparently coming in the new iPad, and it’s a little more interesting than initially expected. The next iPad’s casing will supposedly be capable of magnetically gripping the front flaps of folio-style cases. This could remove the need for unsightly overhanging tabs with snaps, magnets, or Velcro; a thin magnet could be placed inside the front flap to hold the case closed. As soon as the lid’s secured in the right position, or opened, the iPad could automatically lock and unlock itself.

Our source also corroborated what we’ve been hearing from several others over the past week: unless Apple has a huge surprise up its sleeve, or wants to report rapid sell-outs of very modest initial inventory, the next iPad should not ship for a minimum of two weeks, and more likely four. We’ll know for sure a few hours from now.