There's a Clash of Heroes preview and trailer available on GameSpot, along with some other stuff.

What other stuff?

Images!
Trailer!
Preview!

Excerpt from the preview:
The game’s story starts with a bang. A link to the parallel demon world of Sheogh has been opened during a recent lunar eclipse, and it has plunged the peaceful Ashan into darkness. The forces of good once held a powerful weapon known as the Blade of Binding, which bends the will of demons to that of the sword's master. However, in the game's opening sequence the blade is stolen, and it's up to you to find it before it's too late.

The world of Ashan is well realised on the DS, and Capybara has put plenty of detail into the heroes, villains, and environments. The main characters all have their own unique personalities and expressions, while the colour palette is vibrant and the graphics are crisp. Might and Magic: Clash of Heroes is due out on August 25.