In the second half of 2008, the site says, Intel will introduce two low-power versions of Penryn: an LV version and an ULV version, both with ball-grid-array packaging. Those chips will reportedly have die areas of as little as 22mm²—a tiny fraction of the 143mm² die size of current Core 2 Duo chips. According to DigiTimes' sources, the new chips should allow manufacturers to further reduce the size of small-form-factor systems.
Update: It looks like the sizes quoted by DigiTimes are not die sizes as the site says but package sizes. The upcoming LV and ULV Penryn models should therefore have package sizes of 22mm x 22mm.