Civilization V might be getting a second expansion at some point in the future. According to the Steam Apps Database - a website that trawls Steam's huge library - an entry exists for an expansion called "One World". This was spotted by a user of the 2K forums , who was presumably inspired by the addition of spies in Civ 5's last expansion, Gods & Kings.
While potentially exciting news for Civ fans, it's worth remembering that the Steam database isn't an exact science, and a content listing isn't a guarantee of release. Still, more Civ 5 content is hardly outside the realm of possibility. While Gods & Kings had some great additions, it wasn't an all-changing shift in how the game played out.
One World doesn't give many hints as to the possible direction of an expansion. Civ fans are speculating that it may refer to colonies, corporations, or enhanced economy and diplomacy options. Let's be honest though, at this point they're just throwing their wishlist at the wall and hoping that something sticks.
2K have responded to GameSpy's enquiries with the stock "we do not comment on rumors or speculation" line.
Thanks, Joystiq .