I would just like to call your attention to this thread over at the MacRumors iPad forum.
The OP gives fairly compelling evidence that a tactile display is not outside the realm of possibility for next week's iPad 3 intro. Apple even may have obliquely referenced it in their event promo tagline: "We have something you've really got to see... And touch." The tag line for the iPhone 4S/Siri announcement was "Let's talk iPhones." It was innocuous enough on the surface, and only after the fact was it clear that it was foreshadowing Siri. "Something you've really got to see" is likely the much-anticipated retina display, but why the "and touch?" iOS's touch interface hasn't been something worth noting in years. Could it be a tactile display?
Eh, probably not. It seems like a very cool technology that will make it to the iPad in another year or two, but I'm not convinced that it's ready for prime time just yet. But I wanted to post this so that it goes on record that, if Apple pulls this particular rabbit out of its hat, Zweimeter totally called it.