I have one small personal comment to add to Gordon's E-510 review, which concludes above. And that is that, in my considered judgment, the Olympus E-510 embodies the ideal size, form, and weight for a 35mm-style eye-level camera body design.
In Henry Petroski's marvelous book The Pencil, about the "mute history of engineering," he notes that the task of engineering can be distilled to three essences: concepts, magnitude, and materials. With developed technologies, evolution usually comes down to refinements of one of the three. Here, it's magnitude I'm talking about.
In terms of size, shape, and weight, extremes are not what are called for: that is, you don't want the camera to be infinitely light or infinitely small; too small is just as much of a problem as too large—just a different problem. What the designer should be seeking is the optimum balance—neither too light nor too heavy, neither too big nor too small, and just the right shape and form. (I'm not necessarily extending this claim to all the control dials and their placements, although I think the size and shape of the grip and the placement of the eyepiece and shutter release are among the things the Olympus designers got right.) I've personally wondered for years just where exactly the optimum midpoint is for these qualities; every camera of the hundreds I've used is, in my mind, a candidate for overall winner in this respect, and every camera has fallen short, until now.
I won't claim that the E-510 marks any point of progress where concept or materials are concerned; but it is the last word in magnitude, I think...in size, shape, and weight, just what a camera should be, ideally. It could usefully be used by all manufacturers as a model of perfection.
It's possible this might be an idiosyncratic opinion, as, for instance, Thomas Edison's preference in pencils departed from the norm. Petroski tells us that Edison ordered his pencils 3,000 at a time, and that they were fatter than the usual design and only 3 inches long; he liked them to fit in the bottom of his waistcoat pockets. At least I'll claim to be less influenced by "what I'm used to" than other photographers, since I've used so many cameras over the years. So, an opinion, yes, but, as I say, a considered and informed one.
(Incidentally, The Pencil is one of the best books about technology even written in human history, and one of the unabashed masterpieces of the literature of human beings as builders and creative animals—a tour de force of history and culture, not to mention a highly enjoyable non-fiction read, one of the very few books I know of that is worth re-reading. In fact I'm not sure I can recommend it highly enough.)