Here is a list of the strategy games confirmed as being showcased at next months E3, with publisher and developer. This list has been compiled from a number of websites, primarily a master list of games on display from Gamespy.

American Conquest: Divided Nation (CDV/GSC)
Black and White 2 (Electronic Arts/Lionhead)
Blitzkrieg 2 (CDV/Nival Interactive)
Codename: Panzers, Phase Two (CDV/Stormregion)
Ghost Wars (Hip Games/Digital Reality)
The Guild 2 (JoWood/Deep Silver)
Heroes of Might and Magic V (Ubisoft/Nival Interactive)
Hotel Giant 2 (JoWood/Game Factory)
The Movies (Activision/Lionhead)
Pacific Storm (Buka/Lesta Studio)
Panzer Elite Action (JoWood/Zootfly)
Rollercoast Tycoon 3: Soaked (Atari/Frontier Dev.)
The Sims 2: Nightlife (Electronic Arts/Maxis)
Spellforce 2 (JoWood/Phenomic Game Development)
Star Wars: Empire at War (LucasArts)
Tycoon City: New York (Atari/Deep Red)
UFO: Aftershock (Cenega/Altar)
Untitled RTS (Deep Silver)
War Front: Turning Point (CDV/Digital Reality)
War Leaders: Clash of Nations (CDV/GSC)

Stay tuned for updates. Both Civilization IV and Age of Empires III are expected to be exhibited.