The 4/3's consortium is dominated by two major players, Olympus and Panasonic. Until very recently, Olympus, and I think anyone who wanted to produce 4/3's cameras, had to buy their sensors from Panasonic. That era is over and, I've heard, Olympus plans on taking Kodak up on its new sensors.
What's annoying with this situation is that the two primaries of 4/3's are at loggerheads. Any time a company gets a monopoly on something, they will manipulate it. Panasonic has an amazing sensor in the GH1/2, which will never be allowed into non-Panasonic cameras. But all things being equal, Olympus has been making better cameras around the same sensors. Panasonic and Olympus' lenses are compatible, but based on different philosophies. Even the cameras are based on different philosophies.
Panasonic seems to be going after the enthusiast crowd, while Olympus is going after the entry-level crowd. As such, Olympus offers the cheapest cameras, but the worst lenses. All of the same infuriating behavior that we see with other camera companies, who are all desperate to lock users into their proprietary systems, is cropping up in the 4/3's consortium, only in silly and half-assed ways.
Go all out! 4/3's is attractive because it's more open and more group-oriented than Canon, Sony, or Nikon. People want that! Look at Sony, for example, and their NEX cameras. They tried to operate on the same, tired, old business model of proprietary mounts which lock people in, and it failed. Not horribly, but it failed, and look now! Now, they've opened the mount's specifications to other companies in an attempt to build what 4/3's has stumbled into.
Get your shit together, Oly and Panny. Stop butting heads and get your philosophy straight. Straighten out your product lines, start using next-generation sensor tech, and make your shit truly compatible.