The excellent normblog points us to this fine piece. The Libertarians might especially like reading it.

A smoking ban is [an] issue that pits the public good against the liberty of the individual. The public good case for a ban is strong - and we support it. A ban would curb an activity which kills the people who do it or at least damages their health. Not only that, it kills or damages the health of non-smokers exposed to it too. A ban in public places will restrict not just exposure to smoking but also the opportunity and, to some extent, the pressure to smoke. All of this is good, especially in restricting the temptations for young people. The benefits to individual and public health of a ban are not in dispute, as the experience in other jurisdictions has overwhelmingly shown.