I just bought a Panasonic GH1 micro four thirds camera with 14-140 mm (28-280 35 mm equivalent) to replace my shelf full of heavy analogue Nikons and Nikkors. It weighs about half of one of my old bodies plus a 35 and 85 mm lens. I think the micro four thirds standard is the best way forward for lighter high quality camera's. That said, it is still not a light system, far from it.
The heaviest and bulkiest part is this long zoom lens. A 14-45 mm zoom is quite a bit lighter and smaller, and would be enough in many situations. I am holding out here until Leica will market a micro four thirds version of their four thirds zoom in this focal range.
This is of course the biggest of the new micro four thirds camera's, but is has the eye level electronic viewfinder that for me was the reason to finally jump into the digital world. Indeed the two smaller Olympus and Panasonic camera's only have a large lcd, and I still feel that these are unsuitable for serious photography. If I had my way, I would indeed prefer a smaller and lighter camera without the lcd, and only the EVF. A kind of Leica CL. As with that Leica CL the new 20 and 45 mm primes make a perfect combination for those who need the best image quality. The currently lightest combination would be with the Olympus 14-42 zoom (150 gram, but without image stabilization).