I've just published an article on our sibling site, Four Thirds User
, that provides some sample images taken with Olympus' new 75mm f/1.8 medium telephoto. In full frame terms this lens is similar to a 150mm focal length. The lens brightness is also the same as a theoretical 150mm f/1.8, although the depth of field characteristics mean the lens is more like a 150mm f/3.6. But don't sniff - you can still get fantastic blurred backgrounds like this:
Olympus also produces a 45mm f/1.8, or 90mm in full frame terms - pretty much in the sweet spot for portrait lenses. If you maintain the same field of view by bringing the camera closer to the subject you actually get the same depth of field. But the background can look quite different. It's still nicely blurred but look:
Both these lenses are tack sharp wide open at f/1.8, incidentally.