This thread is getting pretty long, but as a FZ20 and Canon 10D and 1D owner, noise on any prosumer camera with a small sensor is going to be more than a large sensor dSLR, period. Most of these cameras (FZ20, FZ30, etc.) will be "acceptable" at ISO 200 and "unacceptable" at ISO 400. My Canon dSLR's have very little noise up to about ISO 800.
Sharpness is very difficult to compare between prosumers and dSLRs. Something I didn't really understand is that the sharpening in a prosumer is in-camera and you can't go back if it is oversharpened. What you see on the LCD or monitor is an image that has been already been processed and sharpened. With a 20D or dSLR (especially Canon) the in-camera processing will be minimal. It relies on you to do this yourself later. Even this requires more work, it gives you more control. So even if a prosumer image on the web may look sharper out of the camera, a lot more can be done with the dSLR image.
I'd base any decision on image quality on trusted reviewers such as Steve, Dpreview, DCResource. They review tons of cameras and know how to use them. To me that's more valuable than various forum members (myself included) with varying levels of skill and experience. Just more thoughts.