May not even be a telco's cabinet . Have seen water companies use similar
It's most likely a water company remote monitoring setup.
Yes, a vertically aligned Yagi aerial is almost always water or electricity monitoring. In this case, from the fact that it's a small street cabinet, it would be water. The Yagi aerials will usually point to the nearest TV transmitter or relay, because that's where the water/electricity companies have sensibly placed their receivers.
The first photo at least, is a water cabinet which monitors flow and no doubt several things I don't know about. They often have a blue plate on them with white text and a simple diagram, giving the most basic (to a water engineer) details of its location and route.
Electricity sub-stations use the same Yagi vertical alignment and usually point at the same "TV" mast (although sometimes to receivers on water towers or mobile masts if they're close and high enough), but they're easily identified - i.e. they'll have a fence and danger of death sign around them.
Wi-Fi would never use a Yagi aerial, because Wi-Fi needs to be omni-directional, whereas Yagi and all other types of "TV" aerial are directional and dependent on either a vertical or horizontal alignment.
Edited by gazzyk1ns (Sun 17-Feb-13 04:19:23)