Cracked Stone Brick

Cracked Stone Brick is a new block type that will be included in the 1.8 Beta update. It can be found in Strongholds, which will also be included in the 1.8 update.

1.8 prerelease 2
as of the 2nd 1.8 prerelease, cracked stone bricks can be obtained by destroying Stone Bricks.

Trivia

 * It appears that, as of 1.8 pre-release, these blocks act like mushroom cap blocks, generating a differing texture once via location.