Facebook – How many facebook friends I can tag on the Facebook photo

Assuming that your friend has a wedding photo with, say, 100 guests in four rows, then he could post the photo twice and tag the front two rows in one photo and the back two rows in the other photo.

That should avoid any angriness amongst his friends.

A 800x600px photo would display each of you friends maximal on a average of 480px. For example a area of 20x24px for each friend. I don't think that one could identify all of their 1000 'friends' to tag them. So answer is no!