Well... when the word "dream" comes into play, many rational factors go out the window - at least with me, I find.
I looked into this thread because I recently got my "dream" camera. Its rather mundane by comparison to the gear already discussed here. Its down right homely by comparison. But please, let me quantify what I mean by dream. When I was a young kid (I am 30 now, so it would be in the 1980's), I desperately wanted a camera like the ones I saw photo-journalists using. I know this was pure chance (it could have been a Nikon, but it wasn't - remember, I was just a kid and knew next to nothing of camera gear beyond the fact that my dad's Zenit was darn right magical to me), but, alas, I saw a Canon camera in the hands of a photog on TV. It had a massive motor-drive (didn't know what it was at the time) on it and it was labelled:"F1". At this point, like I said, I knew nothing of cameras or even of the various F1's that existed - my mind was made up: the Canon F1 was the best camera in the world, it looked as sophisticated as a spaceship to me, and I really, really thought I could never afford one. I collected magazine ads, clippings - you name it, with this mythical picture-taking device in them. I was beyond logical argument.
Fast forward to 2005. Over the years, I learned more and more about cameras. I learned about such magical things as Leica's, Hasselblads and the like - I even learned that as pro-SLR's of the 80's go, the New F1 may not have been the best, probably wasn't in fact. Actually, I have passed buying an F1 on many an occsion, simply out of rational, fiscal reasons (pay less for a camera that can do just about the same things, etc). And I have to admit, now I have dream cameras far more exotic, etc... But, their "dream" status is lesser - it is born out of the logical thought of an adult, rational pros and cons. And while such thought process will undoubtedly yeild a superior choice, they can never come close to eclipsing the monumental dream status generated by the star-struck eyes of a youngster. And so, a couple of friends of mine decided to give me a surprise birthday present some time in advance (in light of the theft of my last SLR) - the choice was obvious, they pitched in and surprised me with a Canon New F1 (I have wonderful friends - that has to be said!)!!!. And when I held it for the first time, a 30 year old man, thinning hair, married, etc., I can tell you that there was no superior camera to that in my hand. The kid inside was on top of the world, and there is no amount of rationale the grown man on the outside could come up with that could rival it.
I know, its not much of a "dream camera" - but like every kid who pined after the black Firebird from Smokey and the Bandit, learning that it was a slow, ill-handling, poorly put together relic has little effect on the fact that there was a time when in that kid's eyes there was no faster, cooler thing on four wheels.
Fortunately, my F1 fairs a lot better than that Firebird - in fact, it does everything I could want a 35mm camera to do and lets me use some wonderful glass - so I guess I lucked out - thank God I didn't pine after an Instamtic

I know it seems that I may have missed the point of this thread - but there is a reason why I went through this lengthy diatribe: while I could sit here and rhyme off spec after spec, what and how I want my "dream" camera to do, I have to tell you that I just did. My dream camera has one requirement -it has to make me feel the way I felt when I finally got my F1.
Cheers,
Peter.