Maybe this explains the absence of Olympus' counterpart to the Panasonic GH1/2.
Rumors are circulating that both Olympus and Nikon will be announcing pro-level gear for mirrorless systems. Nikon's logic assumes that releasing a direct competitor for the Pen and GF2 would more likely cannibalize sales of their own entry-level APS-C cameras, and not steal sales from the 4/3's format. Instead, they're going to release compact gear for professionals, recognizing that many pros have been using Panasonic and Olympus products as walkaround gear because it's so much lighter. I think that the logic is sound. But how "pro" they plan on going is the big question. If they're talking $1,500 or less, I think they've got a deal, but any more than that and I can't think of many professionals who would be interested. Just look at the Olympus E-5. The E-Series has been a success, but not the flagships. Olympus won't talk, but sales of the E-5 are supposedly a fraction of the numbers that Canon, Nikon, or Sony do in the same price range.
The biggest question is, of course, the hardware. As Panasonic pointed out, the larger the sensor, the larger the corresponding lenses are going to be. Will Nikon go for an APS-C sensor and simply charge more for miniaturized lenses? Will they embrace an entirely new format? Considering the incredible quality from the new D7000, I find it highly unlikely that they'll abandon their APS-C sensors. Then, all Nikon lenses would be quickly compatible with an adapter.
Olympus is exciting. I don't find it coincidental that rumors of pro-level gear start circulating right after their contract to buy Panasonic sensors terminated. They're not free to buy sensors from Kodak, who is a bit behind in the noise category, but their sensors work wonderfully without low-pass filters and their colors at low-ISO are among the best in the industry. Just look at the Leica M9.
Even though Nikon is an excellent company, I'm sticking with the 4/3's group. They're the innovators. They're pushing the boundaries. For now at least, Nikon is following, and I'd rather hang out with the guys leading.