Grand Melée, the first expansion for Battles of Napoleon, contains additional game boards, in addition to more than 200 French and British figures that will allow players to reproduce and fight new and especially larger battles, as the boards are modular.
Also Grand Melée will include an alternative set of bases with different colors to create a greater number of unit groups.
The scenarios included are from the Peninsular campaign, the Waterloo campaign, and one from Egypt, with some interesting variations created by "zooming" in and out from the level used in the core set, and a Peninsular War scenario (Vimeiro/Ventosa) which can be played as two separate battles or one larger battle (even if historically the two battles were spaced a few hours apart, it's a reasonable "what-if" that they could influence each other more).
Source: Nexus spring 2010 catalog, and thread/539499/arrived-at-last