On the DVD there are five languages: English, German, French, Italian, Spanish. You can change the language after installation, you can even change it during a running game. The only thing to be aware of are the technology voice overs: when you install the game, you get to choose one language, and the game will only install the voice overs of that language. So if you install the game in English, you can switch to German game text at any time, but you will still hear the English voice-overs.
Another thing to note is that the executable of the German version is 100% identical to the US version. So we probably won't have to deal with month-long delays for patches, with multiplayer not working between different language version, and with mods not working on German versions.
I think Firaxis finally got the localization thing right - two thumbs up!