If they apply it to all workers (i.e. present workers have to quit or lose their job) it's perfectly legal - like Disney and other companies with really strict dress codes. However, not hiring smokers but letting those who are already employed continue to smoke could really set them up for a lawsuit.

Disney enforcing a strict dress code is not the same as discriminating against smokers; the dresscode is what you do while you are at work and bears no restraints on how you dress when you're not working - this is NOT discrimination, it's a rule at WORK. Not hiring someone because they smoke IS discrimination-it's discrimination against smokers.

Ok, I know that I'm getting flamed for this one, but...

I don't think discriminating against smokers needs to be illegal, as smoking is a choice, where being a certain gender, race, age, etc... is not. If a company is looking for a non-smoker, and you really want the job...don't smoke. (Ok, I know for some people it's very hard to quit, but not impossible.) Although to be fair, I do think that they should have to list non-smoker in the job description.