Do Germans still address people as Herr and Frau, or is that a past habit?

Jobst von Steinsdorff

European

To address a common mistake of Americans learning German: You cannot address someone in German with Herr or Frau on their own as you can use Mister or Madam in English. 

(Addition since many comments point out that it is impolite to do that in English, in English it may be bad form but it still is linguistically correct, in German it is already wrong linguistically.) 

Neither in the past nor in the present. You could say „mein Herr“ or „meine Dame“ but that indeed is a bit old fashioned and depending on context people may suspect that it is said in irony. What you can do is use it in third person: „Die Dame ist vor mir dran!“ (The lady is ahead of me (in the queue))

Using Herr and Frau in combination with the surname, as calling someone „Herr Meier“ or „Frau Schmidt“ is, however, perfectly normal.