LGHT

No I was close to the back and we had a fast pace going. By the time you noticed the glass it was already behind you. The only reason it was obvious was because the flats that came shortly afterward.

kbarch

This is why I was taught to say "passing."

Personally, although the precautionary benefit is obvious, I see it more as a matter of politeness than anything - a more cycling-specific way of saying "excuse me!" or "by your leave, sir."
By the way, all you letter-of-the-law Safety Sams out there... You know cars don't honk before passing, right? So why should cyclists "make their presence known" when passing? In the city, bikes are required to have bells, just like motor vehicles are required to have horns, but you're not supposed to use a horn except in an emergency, so you probably shouldn't be using your bell unless it's an emergency, either.

roccobike

You're correct, when racing, you should be prepared for someone to pass you on either side and it won't be announced. When riding in a pace line, passing from the rear is not expected, hence the announcement. I ride in some "A" lines and some "B" lines, depending on the speed and distance. With those lines, we expect riders to stay in place in the line, supporting the group. When racing, it's each rider for themselves. So yes, I understand your point.