@rcarr:
I just think that the WebGUI should be WYSIWYG as much as possible. If NAT->Outbound lists an explicit rule for NATing outbound from the LAN subnet, but doesn't list one for the DMZ subnet, then I should expect that there is no rule in place for the DMZ subnet (which is incorrect).
No, that should only be correct if you're using Advanced Outbound NAT (AON). If AON is disabled, the default behavior is that you will get NAT'ed out the WAN and any OPT interface with a gateway since those are treated as additional WAN interfaces as well. With AON disabled, which is how probably 98% of installs run, you won't see any rules on the Outbound page unless you add them yourself. Even if you do add them, they have no effect unless AON is enabled. That page isn't a display of how your outbound NAT is functioning if you aren't using AON. And there should be no NAT'ing other than what you explicitly define on the Outbound tab if AON is enabled.
There is one known bug related to this right now, see ticket 1289. It looks like the problem you noted may be another bug created by the attempted fix on this ticket.
http://cvstrac.pfsense.com/tktview?tn=1289,6
If you notice other discrepancies from what I described above, it's a bug that needs to have a ticket opened.