As you correctly point out the problem is entirely symmetrical to that of keeping a hot beverage as hot as possible. If we take the different problem of trying to cool a hot beverage, the optimum, pathological solution would be a glass with 0 height and infinite width --studying this problem with the additional constraint that width be limited to some predefined value might make for an interesting followup article.

I guess that the ratio h_open/h_closed is much bigger for hot beverages, due to evaporative cooling. Of course, this would mean that the optimum shape is even thinner than those that were calculated.

But maybe the shape of tee-cups and coffee mugs is optimal, in its own way? I certainly appreciate that beverages that need quite high temperatures for brewing are cooled down quickly to a drinkable temperature.

I think shot glasses are optimized to be put into various configurations, such as matrices and triangular matrices: http://www.likecool.com/Home/Accessories/Billiards%20Shot%20...