I saw a few notes about it too, but I haven't seen the site online in the last few days, not sure what they're talking about (please let me know if you see the site online, I'm only checking a few times a day.
Which brings up a question: Is the gain/loss (including the coinmarket.io problem) charged back to the original accounts, or spread over the current day's account? Since the coins show up as "unexchanged", it can be charged back. Do you distribute BTC on exchanged coins prior to receipt from the exchange? I think coins held at an exchange should show up as "unexchanged BTC_coinmarket", and be distributed when you receive them. Hold them in each person's account as unexchanged. Maybe flag the name of those coins, so we can see our individual exposure.
I think you should only mine coins that are on an established exchange. At a minimum, it shows a certain depth to the market for exchanging the coins.
So, the second part first. Thats what we do normally, the only exception to that was the coins that we had on coinmarket.io, which we've obviously learned our lesson from.
As for accounting side. When coins are earned (immature blocks), they're added as "unconfirmed", orphaning removes them from "unconfirmed", confirmation moves them to "unexchanged". Coins stay as unexchanged until they are sent to the market, are traded out successfully, and processed on our end (note, this
does not include the transfer of BTC back to us). At the current time, I'm not terribly worried about it, only because the chance of us adding another exchange in the short term (until they're large enough) is pretty small, and if cryptsy goes down/gets hacked, we're all pretty screwed anyway. They've recently added an auto-withdrawal API that I need to get implemented, which will help us slightly, but I doubt that it goes around their hot-wallet limits, which puts us in roughly the same spot we are now anyway.