There are several pieces to the puzzle that is the copyright laws of the US. There seems to be more action recently regarding the Digital Millenium Copyright Act, which deals with intellectual property in the digital environment, than there is regarding the "Sonny Bono Act," the Copyright Term Extension Act. There was a bill attempting to amend the latter in 2005 which stalled out in committee. See info here:
http://www.aallnet.org/committee/copyright/pages/issues/ctea.html
The EFF has a page on the DMCA: http://www.eff.org/issues/dmca - if you search their site for "Sonny Bono Act" you get a few hits.
The US Copyright Office keeps a page of current legislation here: http://www.copyright.gov/legislation/
In addition to the academic site mentioned in the first answer, you could also check out Stanford's site on copyright: http://fairuse.stanford.edu/index.html