Sony has announced that it has a new "Exmor APS HD CMOS" sensor coming, offering 1920x1080 resolution AVCHD video in coming DSLRs and in Sony's forthcoming "mirror-less alpha" system. Hopefully this will also lead to improved video in the next generation of Nikon DX and Pentax DSLR's, and the sensor will have some features more specifically designed for video, like the Panasonic GH1 sensor seems to.
At a guess this sensor will have significantly more than 12MP, because once you use every third line from a 12MP in 3:2 shape, the 16:9 image has barely more than 720 lines of resolution, making 1080p or 1080i an upsampled marketing stunt. (22MP is needed to get full 1920x1080 from the every third line method, but with 15MP or more, upsampling to 1080 lines seems worthwhile to avoid downressing to 720p.)http://www.dpreview.com/news/1002/10022103sony2010.asp