According to Steam the following updates have been made to Civilization 5. The patch will automatically be installed when you get online with steam and start to play Civ5.
Official Update text:
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.
I also hope they nerf the steamroll. After all, it was Jon Shafer who, a long time ago at Poly, wrote