The Deutsche Ärzteblatt is the official journal of the German Medical Association, just as the British Medical Journal (BMJ) and the Journal of the American Medical Association (JAMA). Starting January 21, an English language version of the journal will be available.
The publisher and editors of the journal decided to make this step to have the journal articles better indexed in databases such as PubMed and available to more readers. This should lead to more citations of journal articles, resulting in a better Impact Factor and reputation of the journal.
100 years ago, German was an important scientific language, but now only 2% of journals indexed in Medline are in German. I personally haven't written a scientific paper in German for many years. I sometimes regret that I can't use German (or French or Italian for that matter) to report by findings or express my ideas. But in the end it makes the exchange of ideas between scientists much easier if we can all use the same language. And Nature Network is a good example for this.