Yes, in particular to get the date. You can also use undated photos, the visa officers don't usually question them. It's best, of course, if the photos are of obviously differrent times and places - if you look older, have gained or lost weight, changed hairstyles, etc., this is all evidence the photos were taken over several years, even if undated.
We included about 15 photos for our common-law application, none with an official date stamp (although we included date, location, and names of people in the photos for reference).
So far we've only had sponsor approval, but will hopefully hear back from CIC-London soon!