I lean toward Demeter, since it would be more of a surprise reveal. We think of her as the goddess of growth- but her mourning for Persephone each year caused winter and death and misery to which she was indifferent.

From a Guardians of the Gates standpoint, it's been the Fae for at least a millenium. A millenium gone, the Norse gods were at their peak for worship. A millenium before that, the Roman gods; a millenium before that is questionable, but the Greeks nearly align, especially with how Jim plays with his mantles. A millenium before that- Egypt, maybe? A millenium before that, roughly, Sumer, with their mythology of order coming from the slaying of the primordial serpent. Before that, ?- dragons, maybe. As members of the Accords, we've seen Sumerian-speaking ghouls, Etruscan speaking vampires, old Norse gods, and in the background a Greek/Roman deity (is Hades a signatory?).

No real point, just tossing things out there. Millenarian movements are a very real force in human psychology, and Jim seems to be hellbent on creating an "Everything is in it!" series.

Is the story about her creating the summer and winter be a symbolic representation of the division of the elven courts?

I really hope not, it would ruin the entire series for me.

I didn't read it yet, but I believe he made the choice when he left the box of pups that was to be delivered to brother Wang. It would mean he chose to stay with Harry, who was reluctant to keep him and trying to send him back/give him to someone else at first.
Edit: Wong. Brother Wong..

It was Wang in the original story.

It would be interesting to know why so many were in Russian.

https://twitter.com/longshotauthor/status/537078271964622849

Cleanup complete, 700 pages of Cinder Spires manuscript sent off to the editor.  Phew! Jim Butcher

Life is unfolding like it should.

Serack, on a slightly different tack. I have this inchoate idea. After Hades got married to Persephone, there was a deal that she should spend 6 months with him and 6 months with her mother. I thought maybe it really refers to the splitting of the fae (or nature) into Summer and Winter Courts.

Three threads. There may be more.

http://www.jimbutcheronline.com/bb/index.php/topic,41862.0.html

http://www.jimbutcheronline.com/bb/index.php/topic,41686.0.html

http://www.jimbutcheronline.com/bb/index.php/topic,41913.0.html

I was wandering through Goodreads and saw an "expected publication" date of Aug 7, 2014.
Any info on how accurate this might be?

Not really. I have no idea how they came by that date. It hasn't been announced by the publishing company. Serack got any ideas?