Various online toy and card sites have posted the initial release information for the next English Pokémon Black and White Trading Card Game expansion. Dark Explorers will be released on May 9th, 2012 and it will include more EX cards. Darkrai EX, Raikou EX, Tornadus EX and Groudon EX have all been confirmed to be in this set.

Press Release

What's out there in the darkness, waiting to be discovered Play the Pokemon Trading Card Game: Black and White - Dark Explorers expansion and find them all! In addition to more Pokemon-EX like Tornadus-EX, Raikou-EX, and Groudon-EX, the shadows are filled with other exceptional surprises, like Darkrai-EX and a host of Trainer cards that will knock your opponent's lights out! When you play Black & White - Dark Explorers, you'll not only explore the darkness, you'll rule it!

Source: http://www.toywiz.com