I absolutely think it's not only smart marketing, but a reality for smoking different stogies in different seasons. When it's cold a big fat salomon just isn't going to ta happen. When I lived in California, it didn't matter. But in Germany or anywhere else it gets really cold. Not gonna happen. I like short fat smokes anytime of the year but they are a must in the cold.
But I think that's not what your question is. I think you are talking more about a certain flavor profile to fit the season. That to me is more interesting and as far as I know, an untapped niche. Some companies have released summer blends or what have you, but was there a reason that blend fit that season? I don't know. Should it? Absolutely.
That leads to my conclusion; there are already varying sizes, so choose accordingly. We already know we drink different libations according to season so it shouldnt be hard to pair a cigar with that libation. Check this out:
http://www.cigaraficionado.com/Cigar/CA_Archives/CA_Show_Article/0,2322,1334,00.html
And to touch on what was already mentioned, ixnay on the Eggnog, i'll wait for the Pumpkin Pie infused Acid!