According to Steam the following updates have been made to Civilization 5:
Updates to Sid Meier's Civilization V have been released. The updates will be applied automatically when your Steam client is restarted. The major changes include:
Modding - Installer and permissions fixes. Should address any
remaining mod download and install issues.
Full screen crash fix. Game will now restart in Windowed mode if
it cannot find a suitable full-screen resolution on first start.
Hall of Fame now records data correctly when using a Windows
username with special characters.
Deal expiration fixes.
Fix for Puppet State production exploit.
Misc crash fixes.
Modding - Installer and permissions fixes. Should address any
remaining mod download and install issues.
Full screen crash fix. Game will now restart in Windowed mode if
it cannot find a suitable full-screen resolution on first start.
Hall of Fame now records data correctly when using a Windows
username with special characters.
Deal expiration fixes.
Fix for Puppet State production exploit.
Misc crash fixes.