I'm pretty accustomed to shooting JPG and using Picasa.
I've checked monitor calibration and such, and even tried shooting pics of objects that I could easily hold right up beside the image on the monitor for a side-by-side comparison. I've experimented a little more lately with Photoshop CS4, and have gotten some good results, but I still see a difference when comparing the way Picasa displays a RAW image, and the way others including CS4 display it.
While the colors tend to be more vibrant with CS4, I believe that the colors and skin tones are "off" from what we see with the naked eye. Viewing two images side by side, the JPG sometimes seems more appealing to the eye, with brighter colors, darker blacks and shadows, and more "flush" skin tones, but the RAW image, as displayed, seems more life-like, although appearing somewhat washed out, beside the JPG.
I'm scratching my head here. Not certain if it is just my monitor, I'll try uploading some comparison shots this week to see if I can share what I'm seeing.. Honestly I don't think its the monitor.