Nearly a year later, still apparently no announcement - but two comments to that entry, one (a few months back) remarking on the continuing lack of an announcement. And the second one, yesterday, telling me that the first volume is out but under a pseudonym - The Traitor's Daughter by Paula Brandon (ISBN: 0553583808).
No more evidence so far than an LJ comment from someone I had never come across before, but I am rather inclined to believe it. The fact is, I'd already guessed but was unable to come up with any real evidence. Roughly the same publication date as I'd been expecting, the same publisher, a similar title to what previous rumours had been suggesting ("The Traitor's House", if I remember correctly), even the same author's first name - very coincidental but... And, while Volsky was never forthcoming about biographical details, the couple I have picked up about Brandon match Volsky's. What leads me to believe it, though, are details in the advance reviews - the character names feel similar (though not the same), ditto the vaguely Miévillesque non-humans, ditto mechanical intelligences, ditto a story starting in a situation ripe for revolution.
The oddity if so, though, is that the only direct evidence in favour I have had so far is the one LJ comment. I would have expected someone else to have made the connection and mentioned it. And, indeed, quite a few of the reviews obviously regard this as a first novel. But even so, there's enough to make me feel that the commenter was probably telling me the truth. So I had better get hold of a copy and see whether reading it makes me feel this even more strongly.