Case Zero, has been delayed in Japan. According to Andriasang, the delay may have been prompted by some inappropriate content presented in the free trial portion of the game (which can be fully unlocked for 400 Microsoft Points). Capcom assured Famitsu that Case Zero's delay would not affect Dead Rising 2's release in the region.
We're currently following up with Capcom in other regions to confirm the status of the title, which is supposed to unleash its brain-munching masses on Xbox Live Marketplace tomorrow, August 31.
Update: Capcom USA has confirmed that the English release has not been delayed.