Merriam-Webster's Word of the Day for September 02, 2010 is:

vulpine • \VUL-pine\  • adjective
1 : of, relating to, or resembling a fox *2 : foxy, crafty

Example sentence:
"There is something Gatsby-esque about the whole story. [Bernie] Madoff is a clear proxy for Meyer Wolfsheim, the vulpine, self-satisfied criminal seducer." (Daniel Gross, Newsweek, January 12, 2009)

Did you know?
In Walden (1854), Henry David Thoreau described foxes crying out "raggedly and demoniacally" as they hunted through the winter forest, and he wrote, "Sometimes one came near to my window, attracted by my light, barked a vulpine curse at me, and then retreated." Thoreau's was far from the first use of "vulpine"; English writers have been applying that adjective to the foxlike or crafty since at least the 15th century, and the Latin parent of our term, "vulpinus" (from the noun "vulpes," meaning "fox"), was around long before that.