According to Heroic Corner, Heroes of Might and Magic V will be announced next month. They hold that information from a reliable source they can't reveal. Nival Interactive, which is assumed to be involved in one way or another in the development of the game, would make that announcement.
That's the first time there is a reference to a specific timeframe since Fabrice Cambounet cautiously hinted at a post-E3 announcement a long time ago. Still, there is no need to get too excited until the announcement does happen. Thanks to .NET for mentionning those news in our forums.