http://www.japantimes.co.jp/news/2014/08/20/national/haneda-monorail-extend-tokyo-station/#.U_S0gKNqOSo
*Note that other news reports state that the extension is being seriously "studied", which seems less definite than "plans".
nhk report (includes video news report):
http://www3.nhk.or.jp/news/html/20140820/k10013950381000.html
*I have a feeling that JR East (which is a majority owner of Tokyo Monorail) is testing the waters for govt. reaction to this, perhaps fishing for public funding in light of the olympics. They would likely never propose this if there was no possiblity of govt. funding.