It's different in the US. Obama wants to introduce insurance cover so that the 46 MILLION Americans who aren't covered can access healthcare. He isn't (unfortunately) proposing a national health service which would treat everybody - the proposal is to retain private hospitals and reform the insurance system which funds them.
So from this side of the pond, this looks like a slightly kinder version of the capitalist model which has served the US so well (ho ho ho). To many Americans, however, this is communism. Death threats are being made, supporters of healthcare are being beaten up, and now anti-healthcare activists are calling on meeting attendees to bring their guns. What a grown-up way to respond to a weak proposal from a massively endorsed president.
Update:
This is all getting very nasty. American conservatives are spreading lies about the NHS to scare Americans, such as the claim that people over 59 don't get cardiac care, and that Ted Kennedy's brain tumour wouldn't be treated here because he's 77 (well done, Senator Chuck Grassley). Add to this Sarah Palin's description of Obama as 'evil' and her claim that her Down's Syndrome child would face a 'death panel' and we have the makings of a lynch mob. And yes, I'm well aware that that term is racially aligned. There's a nasty undercurrent swirling around Obama which runs 'socialist'-'UnAmerican'-'not born in the US' (untrue)-Muslim (untrue, and who cares anyway)-black-shouldn't be President.
Speak up for the NHS. As Neal points out in the comments, the UK spends less, but spends it better and more fairly. Lots of American pensioners take coach trips to Canada to buy their prescription drugs - pensioners here don't pay a penny (until the Tories get in again) and so don't have to go over to France, Ireland or wherever.