Alien files on some 53 million people will be transferred from the Department of Homeland Security to National Archives and Records Administration (NARA) starting in 2010. This will be a boon to genealogists. Currently the only way to see those records is to submit a Freedom of Information Act request. Once the records are transferred to NARA, they will be opened to the pubic and permanently preserved.
Janie Lorber has written an article about this topic in The New York Times, online edition. You can read the entire article at: http://www.nytimes.com/2009/08/12/us/12archives.html?hpw