Cooking is going to be big in MoP, and not just because of those big panda bellies. At 525 cooking, you can now specialize in different “Ways”, essentially different styles of cooking. Each “Way” specializes in a type of buff food. For example, the “Way of the Grill” teaches recipes that give Strength food.
So why should I level cooking in MoP? At 575 skill, all the different specializations can produce a Feast. This feast will provide +250 to the best primary stat. Once you level cooking (in any Way) to 600 you will get a +275 to your highest primary stat from those same feasts.
If you level all 5 Ways to 600 you will be able to make Pandaren Banquets which give +275 to your highest primary stat. If you master all 5 Ways you will get + 300 from the same feasts.
For comprehensive information about cooking in MoP see this excellent post in the MMO-Champion forums : Rice and Beer: A Guide to Pandaren Cusine.
TL;DR – Leveling Cooking to 600 will give you a +25 stat advantage from feasts.