At this year's CES 2013, Intel gave a rather in-depth look at the fourth generation processor, codenamed "Haswell." It comes with the usual promise of lower power consumption as well as better performance, but it also brought with it a new hardware condition for Ultrabooks.
Notebooks that come with Haswell chips must not only be thin and light, they must also feature touchscreens. According to Maximum PC, future notebooks must also support Intel's Wireless Display (WiDi) if they want to qualify as Ultrabooks.
Source: Maximum PC