As it's been brought up, I was glad to see the Cold Equations reference to Tzenkethi artificial wormhole technology. That was a reasonably big development in Plagues of Night/Raise the Dawn, and I wouldn't want it to be one of those technological breakthroughs with interesting potential consequences that then disappear and are never used or mentioned again.
On that note, I'm equally glad that the thread of Memory Omega will be continued in Disavowed. Travel to and from the Mirror Universe was made so casual in the later seasons of DS9 that incursions are surely expected, and having the significance of the jaunt ships become central to a plot is very welcome. Then again, Mack is good at this sort of thing - I was impressed that Zero Sum Game made use of a captured Breen ship first mentioned in A Time to Kill, for instance - that's a minor continuity reference across about a decade, yes?
One of the reasons Mack is among my favourite Trek authors is that he knows how to use continuity well - detailed, building on what's come before in a natural, organic fashion that sells the idea that this all takes place in one universe, but incorporated so naturally that it doesn't detract from the current story. Unspoken links that carry ideas forward, bring multi-book arcs into play that are evident to committed readers but subtle enough not to trip more casual or sporadic readers. (One of the best examples is the Bacco scene in Zero Sum Game - as I've written elsewhere, it's clearly supposed to recall a similar Zife scene in A Time To Heal, yet it works perfectly whether you've read that scene or not).
Anyway, that's my babbling way of saying "I'm looking forward to seeing the Memory Omega arc's consequences continue through Disavowed".
Although, really, someone should just give the Breen advanced propulsion out of pity, before they bankrupt themselves. Eventually there'll just be a few crazy thots in a run-down room strewn with rubbish muttering violently about slipstream and transwarp while scribbling their plans onto little bits of paper.