Short version of the story - Rambus hid the fact that it was patenting a technology whilst lobbying to have it adopted as an industry standard by the Joint Electron Device Engineering Council. Once the standard was approved they set about suing their competitors for patent infringement. One of the primary defences was that the company acted anti-competitively. The FTC agreed and got involved in the case by taking an antitrust action against Rambus. By refusing to review the case after the Appeal Court had sided with Rambus the Supreme Court are effectively saying their was no breach of antitrust regulations.
The ever reliable ScotusBlog characterises the decision thus:
"Among the cases the Court declined to hear was an appeal by the Federal Trade Commission (not supported by the Solicitor General) testing whether a company’s use of deception to gain a monopoly is a form of harm outlawed by antitrust law. The issue arose in a case involving alleged efforts to gain a monopoly by influencing the setting of a standard for memory components of computers and other electronic devices. The Court made no comment in denying review in FTC v. Rambus Inc. (08-694)."