The company I'm working now (Zest software) has a very healthy attitude on working overtime: don't! That's not something that is automatically so in the IT industry with "death march projects" being proverbial.

Andy Hunt has an article with some of the logic behind not working overtime, 40 hours being considered a normal working week. After 40 hours, your productivity drops. Like Andy says, you can do it for a week or two, but not for the long haul.

So, when I pulled an all-nighter to hunt down (and destroy) a bug last week, I had to promise to take a day off this week. Which I did yesterday, giving me a day to type away at my PhD thesis :-)