NYT Mag article - 'The Tyranny of Copyright'. Nice summary - worth a glance. If you don't wanna read the whole thing, and don't know about the debate, here's the nub:
"...In 1790, copyright protection lasted for 14 years and could be renewed just once before the work entered the public domain. Between 1831 and 1909, the maximum term was increased from 28 to 56 years. Today, copyright protection for individuals lasts for 70 years after the death of the author; for corporations, it's 95 years after publication.
Over the past three decades, the flow of material entering the public domain has slowed to a trickle: in 1973, according to Lessig, more than 85 percent of copyright owners chose not to renew their copyrights, allowing their ideas to become common coin; since the 1998 Copyright Term Extension Act lengthened present and past copyrights for an additional 20 years, little material will enter the public domain any time soon".