It’s Pilgrim’s Bounty in Azeroth at the moment – see http://www.wowhead.com/achievements=1.155.14981
A chance to get some achievement points, a cool companion pet, and a title!
Also, the biggest boon from this World Event is that you can quite easily (and cheaply!!) level your cooking skill up to 300 with a bit of travelling (or portal-ing for mages!).
As with Fishing, Cooking is a secondary skill that doesn’t have level requirements for getting to max level 🙂
As with most things, Dugi has it covered here: http://www.ultimatewowguide.com/blog/2011/11/pilgrims-bounty-guide/
There are plenty of other guides out there, but I love Dugi’s guides (my personal preference).