The Economist reports that WTO delegates recently failed to reach an agreement on "compulsory licensing," which would allow poor countries to make generic copies of patented medicines without the patent-holders' consent. There's no question that, at least in the short term, compulsory licensing would lower the costs of medicine in the Third World--as the article notes, a year's worth of AIDS treatment costs $10,000 if patents are respected, but only $200 if they are not.
The article does a good job of laying out the different positions of various countries, including the US, Japan, and Britain, and it raises some of the more serious problems with compulsory licensing (even if it were allowed).
For those interested in the subject, Bill Clinton recently wrote an op-ed in the New York Times on the issue of dealing with the global AIDS crisis, with a (very) brief mention of compulsory licensing near the end.