In reading through the copious responses to the last post, I was surprised that so many people referred to JPEGs as being like slides (transparencies). Not till MarcB, pretty far down (and Antonio even further), did someone mention what would be my preferred metaphor: that they're more like print-only Polaroids. They're equivalent to development that's done in the camera with the original source thrown out. (A slide is an original; a JPEG isn't.)
At the same time, I have to say that peoples' comments made me much more aware of how much my own choice (I shoot raw) is dependent on a) my history, b) my particular habits'n'practices, and c) my equipment (meaning hardware plus software).
My first digital camera was a 3-MP digicam that shot only JPEGs. Since I constantly pushed its capabilities (I like to shoot in available darkness), I frequently ran out of room for color corrections (the histograms would get alarming "comb" effects), and blown highlights or noisy shadows marred many a shot. So I was hyper-aware of the limitations of JPEGs before I ever heard of raw.
Next, I was amazed that so many people implied that they or others shoot JPEGs because of laziness…because laziness is exactly why I shoot raw! To me, shooting is easier the fewer controls you have to set before you shoot. Having to nail white balance before shooting was a constant pain with my first digicam (on which the auto-WB function was a hit-or-miss affair). The luxury of setting WB after the fact in the raw converter is valuable to me—precisely because I'm lazy. One less thing to worry about. That's a good thing in my book.
Another thing—I don't shoot much. And my method is to pluck out of my shooting just the occasional "hit"—the one shot that gets a complete "yes" response. None of the rest matters much to me. I might only get ten shots a year I like, but for those ten, I definitely don't want to have thrown away any information. I'm also completely convinced that those "hits" can come from anywhere, at any time. So shooting JPEG gives me the same feeling I'd get when I had the wrong film loaded in the camera back in the old film days...it made me antsy, because I was always afraid I'd get a chance to make a "real" picture and miss it because I had the wrong film clogging up the camera. I always wanted to be shooting Tri-X because Tri-X negatives were what I needed for my real work. Nowadays I always want to be shooting raw because I never know when I'll get a picture that I'll want to have a raw file for.
Is it any wonder that a lot of newspaper photojournalists shoot JPEG? Think about it—their work is going to print small, and in newsprint, with color management that amounts to a game of roulette. Of course they wouldn't need raw. That's not necessarily an endorsement for JPEG, just a reflection of the reality they live with.
It naturally depends on your camera and software, too. Carl used to shoot JPEGs with his Olympus E-1 because he was convinced that the JPEGs looked better than converted raw files did. I'm sure he was right. With the K-M 7D and ACR, raw files looked wonderful. You can never extrapolate universal rules in photo-tech, basing general opinions on specific data. Your results are true of the specific chain of hardware and software you use; that evidence can't necessarily be expanded to cover all other cases as well.
Finally, I am (or was, before the advent of digital) a printmaker. And as such, I've always had more faith in my future self than my past self. In the darkroom (I used to do custom printing for a living), I stopped keeping printing records because I was always convinced I could print any given negative better the next time than I did the last time. Maybe that's mostly psychological, but that's always been my feeling. I always want to re-interpret, start fresh, think and judge anew. So to me, having the raw file is simply like keeping the negative. And even with black-and-white film, the print, bad or good, is always just provisional: the neg's the source.
All that said, if I'm a raw-is-best guy, it's just for myself. It just happens to fit the way I work. I don't care what other people do. I think the only reason to encourage people to use raw as opposed to JPEG is if they've just never tried raw and are laboring under the mistaken belief that it's somehow difficult and esoteric and requires huge amounts of time and work. (Here, I can't resist a plug for Michael Tapes' nice video, "RAW Without FUD"—click on the ad at the left.) In every other case, people should do whatever the heck they want to. I never want to shoot JPEG-only again—but that's just me. Other people can, should, and will do whatever works best for them, and I haven't got the slightest little quarrel with that.