Any resolution to this yet? My 2007 has been making a ringing sound for a couple of weeks as well. I haven't posted about it yet because I'm trying to gather as much information as possible, but due to some inconsistencies this isn't easy.
My ringing noise starts shortly (about 30 seconds?) after cold start. Mostly it quits after several miles, but not always. Three times I've come to a stop and put it on the sidestand with engine running only to have the noise go away at that point. It sounds silly, and I suspect is coincidental, but three times? The ringing noise quits after engine shutoff, but twice I turned the key back on without starting the engine and the ringing came on again, but not for long. I must have been dreaming, but that's what I remember. While underway it seems to modulate or "jiggle" in synchrony with shifts, brake application, and some (but not all) road bumps.
Quite a number of times I've tried to locate the sound but without success because it is inconsistent and transient. At times it seems to be coming from the general expanded area of the instrument cluster.
I suppose with the passage of time it will most likely become more persistent and thus be tracked down easier.