So what kind of warning do admins get from bitcoind? Is there something we can grep from debug.log? Or will rpc calls raise some specific error? Is there a way to locally force this to happen, for unittesting services?
getinfo has a new field that shows any alert messages or other errors that would be displayed on the status bar.
The rpc methods return a json-rpc error with the error description "Safe mode: " followed by additional text specified by the alert.
I added the switch "-testsafemode" for you. SVN rev 145.
This stuff is very new and may still be subject to change.
Many switches are intentionally undocumented, like if their functionality is still under construction or I haven't settled on their name yet, or just test code not intended for release.
-4way should eventually be replaced by an auto-detect.