"Prior to Mountain Lion, all processes managed by launchd, including regular applications, had their stdout and stderr file descriptors forwarded to the system log. In Mountain Lion and above, stdout and stderr go nowhere for launchd managed applications. Only messages explicitly sent to the system log will end up there."

(http://stackoverflow.com/questions/13104588/how-to-get-stdout-into-console-app)

QDebug out should be sent to the Console for non-command-line lanched apps.