This game looks to be the Combat Mission of Napoleonic battles. Up to 500,000 men on the field at once, battlefields up to 660 sq km, a great battle editor, the ability to create custom uniforms and an awesome system that models messengers delivering orders who can get lost, killed or captured. The graphics aren't bleeding edge, but they look pretty good and include the option to switch to a traditional 2D view. Really looking forward to it.
Coincidentally, the publishers of this game are also putting out a strategic level addition to Barbarossa to Berlin which packs a mind boggling amount of more awesome into on of my favourite turn based games to date. They are also updating lots of Russian wargames, giving them an English release as well as lots of gameplay improvements. Check out their site if you don't know it already.