Recently one of my favorite sites, 43Rumors, posted an article about the new Olympus 300mm f/4 lens. I thought it looked a lot like a lens I already have, the Nikon 300m f/4. What do you think? The difference of course, is that the Micro Four-thirds format has a 2x crop factor compared to 35mm full frame, so that means this would be a 600mm lens on any M43 camera - but with the added advantage of image stabilization. This raises all sorts of possibilities for hand-held (or monopod-aided) sports photography, particularly with 10fps shutter speed of some M43 cameras.
I'm getting excited. So I pulled out a few action photos that I've taken with the 300mm f/4 lens on my D700 and D800.
It's also not bad for landscape photography, even hand-held (as these were):