Right now, there's a request before the FDA to allow other vegetable fats to be substituted for the cocoa butter in chocolate. There aren't very many vegetable fats that are naturally solid at room temperature, so mostly what they're talking about is using hydrogenated products.
Chocolate is a health food. It protects the heart. Hydrogenated oils contain trans fats, which cause cancer and heart disease.
Manufacturers can already make products using vegetable fats instead of cocoa butter. It's called "imitation chocolate". The only change this rule would make is to confuse consumers.
Time is getting short, but you can speak out on this issue. There's a page at http://dontmesswithourchocolate.guittard.com/howtohelp.asp that explains how you can complain to the Food and Drug Administration.
That page says to use their form letter. If you prefer to register your opinion in your own terms, please use caution. If you use bad spelling and grammar, and rant like a nutcase, your comment will be taken lightly, as if it came from an illiterate loon. If you are well-spoken, on point, polite, and follow the rules of grammar, they'll assume that you are a community leader, who has given this matter significant thought, and who is not to be dismissed lightly. If you're not sure, feel free to use the form letter.