Patch 4.2 will release the next level of raid content, and is likely to be released on June 28th (although Blizzard reserves the right to postpone it, etc., etc.) Here's the things you should know about it:
1. It will include an upgrade in gear level. The current stuff you can buy for Valor points will be able to be purchased for the same number of Justice points. So, you can get 359 level gear for Justice points. New gear of level 378 will be purchasable for Valor points. HOWEVER all your existing Valor points will be turned into Justice points. You can only have a maximum of 4000 Justice points, anything more than that will turn into silver pieces. So, look at the total of your Justice and Valor points--if it is more than 4000, go buy something. The Justice point trade goods vendor has stuff for only a few hundred so you can tweak your amounts.
2. It will introduce new dailies and other new quests. These quests (eventually) result in some 365 level gear, and recipes for 378 level gear. If you have not finished the Mt. Hyjal quests, there are some pre-quests that you will need to do, so it is recommended that you finish Mt. Hyjal. Start the quest chain by, you guessed it, consulting the Hero's Call board.
3. It will introduce a new faction from the raid (think Ashen Verdict). There are rewards for building this faction up as well. (My joy can hardly be contained.) There is a new quest for a caster legendary that begins after killing a particular trash mob in the raid instance.
4. Valor points are available from random heroics (2x as much from the Zandalari as the others) and killing the new raid bosses, or the heroic modes of the old raid bosses. There is a maximum of how many valor points you can earn in a week.
There are a lot of details I've left out, ask up if there is something of concern. There are also a lot of details not yet released.