How you handle it depends on the desired outcome.
If you don't want to work somewhere where 60 hours/week is the norm you say this:
I consider it unproductive and
unreasonable to work 60 hours/week on
an indefinite basis. It indicates poor
planning and a company culture that
doesn't value programmers and the
processes that require good code.
For good measure, throw in something about a healthy work/life balance, particularly if you have children.
The result? If they think it's a problem they'll respect your answer. If they think it's reasonable they'll not like your answer and you won't get the job. But that's OK, because you didn't want that job anyway.
Never forget that when an interview is taking place, the interviewer is interviewing you but you are also interviewing them. If you go in with the attitude that they have all the power then you're selling yourself short and giving them all the power. The goal isn't simply to present yourself as best as you can and hope they hire you. It's to find out if they want you to work for them and whether you want to work for them.
Now if you're in a position where you have to get a job that's a bit more unfortunate because you may have to be less picky than you'd otherwise be. A good answer along those lines is something like:
I'm interested in getting the job
done, done right and done on time
where possible. If you're watching the
clock then you're in the wrong job
since you should like what you're
doing and want to do it right.
As for working hours, it varies a lot by industry. The games industry is famous for having "crunch time", which can be insane hours in the lead up to a release to get it out the door but other periods of lighter loads.
Consultancies tend to be good from the point of view of avoiding long hours because you're doing something (most of the time) because your company is being paid for it to be done. This can mean that you don't work insane hours because noone will be paying for that. This can of course vary.