You may know the profile-tagging feature when you post from the publisher in Facebook. There is one thing that is inconvenient: if you tagged some profiles in a Wall Photo and then you want to edit the caption, all the tagged profiles will be untagged and come back to normal text. Fortunately, you can now manually tag profiles in photo caption by using the syntax
@[Facebook UserID:Facebook Name]
Very simple, if you want to tag profile called "A Friend Of Mine" and his/her UserID is 123456, just go edit your photo caption and type in @[123456:A Friend Of Mine], save the caption and you are done! The tagged profile will receive notification as usual. I'm not sure if there is any limitation so... try it and tell me if you run into one. Happy Facebooking!