From the link to this Japan Times article:
http://www.japantimes.co.jp/news/201...osaki-station/
New low-cost bus service (1,000-1,200 yen one way) to start operating from October this year connecting Narita to Osaki Station in Shinagawa.
Although it doesn't mention how long the journey would take, this could be useful for people who are headed towards Shinagawa and further south and are looking for a low-cost option for airport transfer that doesn't involve changing at Tokyo Station.
Also:
Shibayama, one of the municipalities in which Narita airport is located, has been selected as the last stop at the Chiba end of the bus route. This is a bid to promote areas around the airport.