In its Quiet Mode, the D5000 is the quietest Nikon ever.
The D5000's Quiet Mode is a shutter release mode selected in the Info Screen in the same place you choose Single, Continuous, Self Timer or Remote Control. It's at the very bottom, where you won't see it unless you click all the way down. Quiet Mode is a regular shooting mode not related to Live View. In Quiet Mode, you get one picture every time you press the shutter.
Quiet Mode slows down the mirrors and mechanical junk that has to fly around inside the D5000, which makes it much quieter. This adds a tiny delay between when you press the shutter and when the mirror flips up and the picture gets taken. This is a small price to pay for quiet; remember, in the situations you use Quiet Mode you're working very delicately.
The D5000 in Quiet Mode is even a tiny little bit quieter than a Leica M7, which is the cloth-shuttered rangefinder camera used by modern journalists when they need a quiet camera.
The D5000 in Quiet Mode is far quieter than any digital Nikon SLR, and far quieter than the Nikon F, Nikon F2, Nikon F3, Nikon FM, Nikon FE, Nikon FA, Nikon F4 in its own quiet advance mode, and even a little quieter than the Nikon SP and Leica M3 mechanical cloth-shuttered rangefinder cameras from the 1950s.
There are no SLRs anywhere near as quiet as a D5000 in Quiet Mode.
Not only is the D5000 the same as, or a little quieter than the LEICA, the D5000 winds itself at the same time, while the LEICA still needs to wind film. (Forget the LEICA Motor-M, it's noisier than thumb-winding.)
The fact that the D5000 is at least as quiet as the Leica M7 means it probably also can replace the Leica M8.2 for journalists. Sorry, Leica; this was Leica's last remaining professional stronghold.
To sum up, the D5000 in Quiet Mode is as quiet as the LEICA. After 50 years, Nikon SLRs have stuck it to Leica again. The Minolta CLE and Zeiss Ikon are louder, and any other SLR is like a metal band by comparison.
Not even the D5000 or the LEICA is quiet enough to shoot politely from the audience of a live performance. For those, you need to shoot the dress rehearsal or from behind glass in the recording booth.
