Toady, during the clean up for the last release you spontaneously (Well, it seemed spontaneous to me) added minecarts and changed how hauling of stone was handled. Would you mind speculating wildly about things you'd like to add and change during the bugfixing rounds next month? Or, if that's too much of a strech, what do you see as the next arc to work on after the current release is cleaned up?
So far, he's mentioned the
trade interface in a facebook post, and
job priorities in the June report. In that second link, they also suspect "that many of the faster usability ideas will make it in during the bug-fix period and during the job priorities work that'll follow this release".
As for the next big thing, it's anybody's guess at this point. The
dev page for the next year or four is the most reliable source for speculation; there was another page related to that one with a rough estimate of the order in which they were going to work on that stuff, but that order got all bjorked; this release (Phase 2) was originally just planned to be civ sites and mine maps if I recall (I haven't actually tracked down that second page yet, if it still exists), but they decided that they needed post-worldgen history (from Phase 5 or so) sooner.
EDIT: Looks like that other page was just part of the main dev page, in which case it's gone now (and rather outdated and wrong anyway). It's too bad the wayback machine's banned from the dev page for bandwidth reasons, it'd be neat to see some old incarnations of it (we still have
the really old one, though).