An investigation by the Government Accountability Office, a nonpartisan investigative arm of Congress, has found that Plan B's rejection by FDA was a foregone conclusion. That is, FDA had decided not to approve over-the-counter sale of the "next-day pill" before the manufacturer's application had been through the scientific review process.
According to an article in the New York Times, top FDA officials were "deeply involved in the decision," which is unusual. The GAO's findings have been denied by FDA leadership. There's a lot of he said/she said going on, from the looks of things.
The drug prevents pregnancy if taken within 72 hours of unprotected sex. It has been targeted by anti-abortion activists, citing concerns about use by minors and the use of Plan B (and similar drugs) in place of contraceptives.