Read post #23 by Publius, who has it right. When the government attempts to restrict sales, then that is the only proper definition of censorship [and censorship is not the 100% bogeyman that it's made out to be by liberals; some things--like obscenity--need prior restraint).
Example: Fans who choose not to buy Dixie Chicks' CDs or concert tickets is NOT an example of censorship (banning). It simply shows a market-savvy public at-large.
Likewise, if individual radio stations or corporate chains of radio stations choose not to play the Dixie Chicks, that is NOT censorship/banning; that is the free market at work.
However, if you have government officials come along and tell radio stations NOT to air the Dixie Chicks, then THAT would be weighted more as an attempt to ban rather than merely boycott.
Distinction between ban and boycott: If the Jersey pols were appealing to potential buyer-readers, then that is weighted more toward a boycott. When the appeal by government officials is to retailers not to stock a certain item, then the appeal is weighted more toward a ban. Obviously, there is no attempt for a total ban here. I am merely talking on a continuum scale.