There are HPS bulbs that I know of that are designed to hang vertically but there MUST be extraction through some kind of cooltube. The plants have full 360degrees coverage from the bulb and not just half you get when hanging horizontally but I'm sure theres some hidden price to pay for growing this way. Also the first pic looks like that because he has trained and topped his plants, there's nothing to say that the results would not have been the same or better if the bulb was horizontal.