I am no constitutional lawyer so I can't say that, in this case, obiter dicta doesn't apply. But there are cases where obiter dicta has ended up as long-standing precedent.
Just to be clear, I disagree with the decision to uphold Obamacare, but I don't consider it any disaster for the Constitution.
No, there aren't. Orbiter dicta is not precedent, and no lower court nor USSC is bound by dicta.
A very thoughtful opinion and some links to counterpoints by someone whose opinion I am very proud to say supports mine just came online about 1/2 hour ago (none of these are my blogs) here: http://legalinsurrection.com/2012/06/what-if-that-huge-conservative-doctrinal-achievement-was-mere-dicta/