It is winter solistice for those of us in the northern hemisphere; it is the summer solistice for those who live in the southern hemisphere.
While Golden Dawn does not officially have a solistice ritual, a remarkable oversight in my opinion, as a wiccan and pagan, I do observe the solistices. I am not such a big observer that I will go and drum up the sun at Red Rocks (it is just too cold to do that in my opinion, even when it is not sub-zero temperatures); but in my own small way, I note its passing.
Mainly I start to pull out the seed catalogs and think about what I want to do in the garden this coming season. Later I will consult the wife about my plans.
Personally, I think that it does a person good to be aware of the passing of the seasons. To know and remember that every thing has its own season is a valuable piece of esoteric lore; esoteric not because it is hidden away from the masses, but esoteric because so many people have forgotten this law of nature.
If you can remember that things come and go, waxing and waning in their strength, you are less likely to be surprised when things crumble. Often the practical benefits of our tradition lies not in the powers that we develop; rather they lay in the patterns of awareness that we inhabit.
For instance, if you can look upon the economic bubbles and the adventures of mismanagement and connect them with the Kings of Edom, remembering what happened to those proud and arrogant Kings, then you will not be surprised when the bubbles break and the energy of the blasted tower comes flashing though.
As Paul Foster Case used to point out, the symbolism of the esoteric sciences are only useful if you make them a part of your mental furniture.