The article's a mess. The basic point is that most DSLRs, except for the true high-end "full frame" models, have sensors that aren't as big as 35mm film was. So the big 35mm SLR lens is partially wasted, focusing light in areas where there is no sensor.<p>So there's a new class of high-end cameras that take the same smaller sensor size and pair it with interchangeable lenses. That produced the four-thirds system (<a href="http://en.wikipedia.org/wiki/Four_Thirds_system" rel="nofollow">http://en.wikipedia.org/wiki/Four_Thirds_system</a>). Then if you remove the optical viewfinder and mirror, you get the even smaller micro four-thirds system (<a href="http://en.wikipedia.org/wiki/Micro_Four_Thirds_system" rel="nofollow">http://en.wikipedia.org/wiki/Micro_Four_Thirds_system</a>).<p>They're a great system for the "prosumer" or high end amateur photographer. You get essentially the same quality as the lower-end DSLRs with smaller cameras and lenses.<p>The only downsides are that so far they seem to be more expensive than the low-end DSLRs and I think lots of people just like carrying around a big black camera with their long kit zoom lens on it.