The U.S. House Committee on Transportation and Infrastructure approved a proposal to consider using a public-private partnership to boost the Acela Express's speed on the Northeast Corridor. They plan to cut the time between New York and Washington DC from 2 hours and 45 minutes down to less than two hours. The cost? They would need at least 14 billion dollars to make it work.
Some of the concerns include the probability that the private sector would want to invest so much money into Amtrak. However, the Northeast Corridor is the only Amtrak line that's actually making a profit, so it may not be a bad idea.
You can read more about this proposal in this article in the Delaware Online news journal: http://www.delawareonline.com/apps/pbcs.dll/article?AID=2008805290340