And the official 2kgames site, with a few bits of artwork: http://www.2kgames.com/civ4/beyondthesword/Features:
Expanded Epic Game: Firaxis Games delivers a massive increase in new units, buildings, and technologies to the epic game with additional focus on the late-game time periods.
New Game Scenarios: The expansion will deliver 12 new scenarios, many containing themes never before included in the Civilization series, custom designed by the team at Firaxis and select members of the Civ Fan Community.
New Civilizations: The expansion pack includes ten new civilizations, such as Portugal, Babylon and Netherlands and their associated unique units and buildings.
More Civilization Leaders: Sixteen new leaders including leaders for the ten new civilizations, as well as additional leaders for existing civilizations.
Corporations: A new gameplay feature that allows players to create corporations and spread them throughout the world. Each corporation provides benefits in exchange for certain resources.
Espionage: Now available much earlier in the game, this expanded feature offers players many new ways to spy on opponents, stir citizen unrest and defend their government’s secrets.
Events: New random events such as natural disasters, pleas for help, or demands from their citizens will challenge players to overcome obstacles in order for their civilizations to prosper.
New Wonders: Five new wonders await discovery including the Statue of Zeus, Cristo Redentor, Shwedagon Paya, the Mausoleum of Maussollos, and the Moai Statues.
Expanded Space Victory: Winning the race to Alpha Centauri will now require more strategic planning and tactical decision making.
Apostolic Palace: The United Nations will become available earlier in the game, providing a way for players to win a diplomatic victory earlier. New resolutions will also be added which will expand the available diplomatic options.
Advanced Starts: A major fan request, this new feature will enable players to “buy” components of a custom-tailored empire and begin play in the later part of the game, allowing them to experience many of the new features of the expansion pack in a shorter amount of time.
Enhanced AI: The AI has received many enhancements, making it tougher to beat on the higher difficulty levels. The ways in which the AI will attempt to achieve victory have also been expanded.
Woo! Some interesting stuff in there! July isn't that far off either
