Nasty87MFT sensor allows for significantly smaller, lighter lenses at lower costs. Try lugging an 800mm ff equiv lens around; try using such a behemoth w/o a tripod. MFT is, in fact, the ideal format for long-reach lenses. The price on this drop is fair (though certainly not great); the issue I have is the ship date isn't until early/mid May.
Nasty87The portability of quite reasonable zoom lenses is actually a very attractive part of the m4/3'ds format. That said, when you get into the more pro glass I think the trade offs start looking worse as the lens weight goes up. I think something like the Panasonic 100-300mm II might not be as nice glass-wise, but is maybe preferable from a portability standpoint.