Smokers, it seems, feel like they're once again getting the short end of the stick. If some of the quotes in this article are to be believed, Massachusetts, is one place where it is fine to not hire people who smoke.
One has to wonder if this is any different from the fat guy who isn't hired due to a lack of "personal hygiene" or glossing over the application of the unattractive applicant for the customer rep position.
As a non-smoker who grew up in a smoking household, my gut reaction is "too bad". Smoking is a choice, unlike the other criteria that count as discrimination under law.
Most companies that I have worked for in the US and in Europe have done their level best to accommodate smokers in the workplace. This has ranged from an outside area with ashtrays, a ventilated room, or a separate area of the break room. They have, for the most part, have also been tolerant of smokers who couldn't help themselves and drop cigarette butts either in the lobby or in front of the building.
What smokers might not understand is how their activity affects their own appearance or others. If a candidate walked in with a strong, unpleasant body odor, they would likely not be hired for that very reason. It would be a difficult issue to deal with and one that would likely disturb the balance of the team.
Smoking is not much different. The candidate (and yes, I realize that not all smokers fit this mold) who comes in with smoke on their breath and in their clothes is not likely to win him or herself many points. It creates an unpleasant distraction.
While these reasons may not be sufficient to smokers, they are likely what's on the mind of the recruiter or interviewer when you're looking for a job. Instead of looking for someone to blame for discrimination, why not look to solving the problem?