You can stop writing your META keywords now, folks.

A United States court has declared, within a ruling regarding trademark infringement (Standard Process, Inc. v. Banks), that META keywords do not influence search results:

Court Declares META Keywords Dead
U.S. Court Learns SEO, Decides META Keywords Don't Matter
Court Says Keyword Metatags Don't Matter--Standard Process v. Banks

Dr. Banks apparently (amongst other things, it seems), used some of Standard Process Inc.'s trademarked terms within his own META keywords. The court felt that the trademarks used in the META keywords were immaterial since META keywords aren't even used to influence search results anymore.

This remark by the court seems to overturn an earlier ruling—just this month—declaring that the use of trademarks in META tags can constitute infringement:

US Court Rules Trademarks In Meta Tags Can Constitute Infringement

Regardless, scrap your META keywords. Your keywords belong in your site's copy.