Here's the amicus brief filed today by Pacific Legal Foundation in Mehaffy v. United States, No. 12-1416 (cert. petition filed June 5, 2013).
That's the case in which the Supreme Court is being asked to review to review the Federal Circuit's unpublished opinion in which the court affirmed the Court of Federal Claims' grant of summary judgment to the government, holding that Mehaffy failed the Penn Central test solely because he purchased the property alleged to have been taken after the governmentt adopted the Clean Water Act.
PLF has posted a more in-depth summary of the case and the arguments in its brief here.