Here's a NYTimes article on the law:
The legislation, which President Bush has indicated he will sign, speaks both to the mounting hope that genetic research may greatly improve health care and the fear of a dystopia in which people’s own DNA could be turned against them.Here is the text of the bill. The House passed it 414-3 (3 Republicans including Ron Paul opposed it), the Senate passed it 95-0, and Bush is expected to sign it - this bill is even less controversial than Mother's Day (which Republicans voted against!). The fact that this bill was so uncontroversial signals an unease with the basic premise of private health insurance.
On the House floor on Thursday, Democrats and Republicans alike cited anecdotes and polls illustrating that people feel they should not be penalized because they happened to be born at higher risk for a given disease.
...Many who do learn that they are at higher risk for a disease opt not to ask their insurance companies to cover the costs of the genetic test, to keep the information secret.
...While the intent of the law is to prohibit discrimination by insurance companies based on genetic tests, the bill does allow the companies urge patients take them. The goal would be not to deny coverage but to help find the best, and least expensive, therapy for a patient.
Genetic screening would be a normal part of any insurance underwriting process - trying to screen out high-risk customers so the insurance company doesn't get bogged down solely with expensive patients. Right now apparently about one in eight people who apply for health care individually are denied through the underwriting process, and even more are forced to pay higher premiums (pages 8-10). Some of the reasons may be under a patient's control (smoking, etc.) while others aren't (chronic diseases, family's medical history). This is distasteful but necessary to any method of paying for health care that does not agglomerate all potential patients in a single risk pool (single-payer).
Nothing separates screening out patients with a genetic predisposition towards expensive illnesses, and patients with chronic yet dormant illnesses that may have expensive flare-ups in the future (both have current low costs but a high risk for future high costs). Congress outlawed the former because the concept of genetic screening is icky (a technical term). The later is legal.
A lot of conservatives like to blather on about how the free market will fix the way we pay for health care. Companies succeed in the free market by increasing revenue and cutting losses, which is exactly what Congress just outlawed. This is not evil behavior - if a company gave coverage to anyone who wanted it, it would go out of business and not be able to cover anybody.
Some people say that the government can pick up all the really sick people that are uninsurable. All that does is privatize the profit (from low-risk insurance policies) and socialize the risk.
Free markets are great for some things, like selling my fridge. They are not great at charity and ensuring that the least fortunate in society are taken care of. Universal single-payer health care is the way to go.