Gamespot reports that yet another publisher has joined the ever-growing stable of Steam fans. 2K games is working to bring some of their games to the service, with Civilization III and IV coming to Steam this week, and other titles to follow. From the article: "Also included will be the high-seas adventure Sid Meier's Pirates! and the alternate-history real-time strategy game Shattered Union ... According to a statement released today by Valve, Steam currently has some 10 million customers for both its 'core' products--which include advanced shooters such as Half-Life 2--and casual games, such as PopCap Games' Bejeweled and Zuma. "