A news item on the official site confirms today that Might and Magic: Heroes VI has been delayed until September 8th:

"Dear fans, Might & Magic Heroes 6 release date has been postponed to September 8th. We want to ensure that the quality of the game will go beyond your expectations! Stay tuned to learn more about the game and the upcoming beta as we’ll continue to update you about its development!"

No word on whether this delay will have an impact on the upcoming beta testing.