This was posted in a recent article on MousePlanet.com by Marc Goldhaber:
"Business casual" restaurant requirements
We've received a number of emails and posts on our discussion forums recently about the dress code now being enforced at several restaurants on Disney property. Guests are being caught unaware that this policy is now in place. As a public service, here are the rules and locations. Artist Point, California Grill, Citricos, Flying Fish, Jiko: The Cooking Place, Narcoossee's and Yachtsman Steakhouse all require "business casual" attire.
Business casual is defined as follows: Men: Dress slacks, jeans, trousers, or dress shorts, short or long-sleeved shirt with a collar required. Jackets are optional. Ladies: Jeans, skirts, or dress shorts with blouse or sweater, or a dress required. Not permitted in dining room: tank tops, swimming suits or swim suit cover ups, t-shirts, hats for gentleman, cut offs, or torn clothing of any kind.
Victoria and Albert's continues their existing dress code. Dinner jacket is required for gentlemen (tie optional) and dress or pants ensemble for ladies.