My United flight wasn't diverted, and so we got no announcement. It wasn't until after landing that a government official told us what had happened and that we should check the news.
From people I know on diverted flights that day, their messages -- if any -- were mainly about diversion due to airspace restrictions or ATC.
LH had just started in-flight Internet on some flights several weeks before 9/11, but I don't recall live TV in first on LH that year.