Now that the Crystalline Catastrophe event has run its course, the Z:D Exchange seems to be returning to more "normal" volumes. The rate seems to have stabilized for now, but I expect it to start moving again once Legacy hits. Returning players means more Dilithium entering the market, but also means more Zen entering it. I'm not sure which way it'll go! That said, hopefully there will be a nice influx of new players.
As a point of contrast, Neverwinter's new economy is running significantly lower numbers, and its top 10 rates have a 9-point gap between them! 1:384 and 1:375! Once in a while there'll be a 1-point gap in STO, so this is quite a sight! Some people are blaming the mass amounts of Astral Diamonds in the Founder's Packs (600,000 and 2 million in the Guardian and Hero packs, respectively), however I'd imagine they're still unrefined, thus capped by the 8,000/day refinement limit. Note that Cryptic chose not to do that with the Romulan Founder's Packs, opting to include Master Keys instead. Additionally, the one would think that the sheer number of players engaged in the Crystalline Catastrophe event that earned 50,000 Dilithium should've had similar effects if the Founder's theory is correct.
While the Founder's theory has some potential, I personally look more to the fact that the game is still in beta, and (hopefully) only has a fraction of its potential playerbase at launch. Also, I don't think its got the same level of things to spend its time-currency on like STO, nor does it have as much in its shop as STO. It'll be a while before the developers get things where they want it, if STO is any indication of what is preferred. Right now its incredibly pro-Zen, making it an unfavorable environment for players trying to earn Zen. Star Trek Online is the better of the two for now in this regard.
Its fascinating to see this new economy emerging, especially since I missed the period of time when STO went F2P. I suspect we'll see Neverwinter adopt things we see now in Star Trek Online, but I could well be wrong. Anyhow, that's enough musing; onto the data!