Here's a visual. 1 (Click for larger.)
In this graphic, which is not at all inclusive, you can see, for example, that the blue bubble, Hain, owns many green-bubble organic offshoots. A few of Hain's principle stockholders are ExxonMobile, Phillip Morris, Citigroup, Pfizer, Merck, etc.
Here are some details:
The USDA and industry lobbyists are (right now!) pushing a bill in Congress to lower organic standards. The rider to the 2006 Agriculture Appropriations Bill would allow undisclosed synthetic ingredients in organic foods, and most disturbingly, would shift control over organic standards away from the National Organic Standards Board (NOSB) and into the hands of the federal government (who in the past have recommended that genetically modified foods, irradiated foods, and foods containing previously banned pesticides, hormones and other drugs fall under the umbrella of "organic".)
If you're interested in sending a letter to your representatives, the Organic Consumers Association has made it easy:
Send a Letter!