DotNetNuke 3 was annouced as the first multi-language version. This is not completely true, as the core team only provided static translation - this enabled portals in any language, but only one language per portal. And currently there are still some items not covered by localization: lists and module names. Anyway it is a big step ahead.
The Core team decided to provide 2 languages within the standard daployment: English and German. As we found, that their german translation could be improved, we decided to work it over and rewrote all the texts, trying to provide an adequate german wording for most of the technical terms, so even novice users of the internet can handle the system. We are proud, that the core team decided to imtegrate our translation within the standard deployment.
In DotNetNuke 3.0.13, the German Translation has been surprisingly removed from the standard deployment and has to be installed like any other lnaguage seperately. You can always download the current Language Pack from this site.
Currently DNN 3 is developed simultaneously with DNN 4, having the same functions. This shall end after release 3.3.x You can always migrate to the current DNN 4 release without mayor problems or risk of data loss.