Pew Research has put together this really nice piece summarizing all the recent polling on the Affordable Care Act compared to polling done right after it was passed in March of 2010. Basically a few polls show it getting slightly more popular since it was signed into the law and a few polls have it losing support. From Pew:

Overall, net support for the law remains little changed from two years ago. The only real change is that all the pollsters, except Pew, find slightly more people currently have no opinion or are undecided about the law.

It is possible the Supreme Court ruling could change some minds, but given the relatively stubborn constancy of the polling, I doubt even the decision by the highest court would move public opinion that much. I suspect opinions about the law won’t change significantly unless and until its major features  start being fully implemented in 2014-2015, or unless it is repealed in early 2013 by a surprisingly victorious Republican party this election.