The official announcement from Facebook is today, but there are tips floating around the interwebs. Below are a rundown of some links to check out.
This is an opportunity for restaurants to really think about how you graphically represent your brand. There's a large "cover" image that will go at the top of your page. It's not supposed to be self-promotional or spam-y.
I'd say either go creative (if you have access to a graphic designer) or go simple/human. Share the look and feel of your restaurant. Show off your your food with a vibrant photo. Give a sneak peek of the interior of your restaurant. Maybe even host a contest in March for people to submit photos for your first cover!
Here are some details about the new pages that are worth checking out.
Also, take a look at what some food brands are doing with their new pages