Some companies have actually moved towards a more "flex time" model. Basically, employees were not required to work a 40 hour week. They are only required to work when they have actual work to do. And, so far, Best Buy claims that productivity is up.
I think this is a great idea - and I'm not the least bit surprised.
Working in IT (and for most companies) means that there are times that are busier (more hectic) than others. I've worked in various IT organizations for the past seven years - to give you an idea of my experience. Yet despite the fact that most IT employees are salaried (not hourly), most of us have to put in a 40 hour work week. And work overtime when expected.
This is because:
1 - Most IT hours are billable
Much like the law or accounting professions, IT hours are typically billed somewhere. If a company is a large, public firm, they need to show a certain number of hours billed outside the company or to various projects.
If someone is working 36 hours and another person needs to work 40 to get the job done, it makes a difference in the billing.
2 - If someone's not working all their hours, maybe they are a surplus employee
Sadly, this is still the prevailing view in most IT organizations. With razor thin budgets, management tries to cut any overhead or surplus wherever possible and also outsource. With most organizations I have worked for, everyone always wants to appear that they are super busy all the time, in order to increase the number of employees. No one should ever ask for work or say they aren't busy.
(Sound like dilbert yet???)
3 - Managers would be required to actually pay attention to what their employees are producing
To make sure that everyone is tasked without being over tasked. Anyone who has ever been a manager before knows that some employees can do the same tasks as others in different time frames. Most managers are happier with an employee sitting in their cube (or on an instant messager system) than knowing whether or not they're actually being productive.
4 - Some people will still want to work extra to try and get ahead
No matter what management says, if someone is up for a promotion and you have an employee who works 38 hours a week and one who works 50 hours a week, and they both produce great work - the employee who works fifty hours will probably get the promotion. It's the way it's worked in many organizations for a long time.
So, for these reasons and others, I think that a flex time (only work the hours that you have actual work) is probably not going to happen in large IT organizations any time soon. And, it's actually a shame, because it would improve morale across the board.
And many smaller companies and organizations already have this as a benefit.
I'm just thinking for the larger fortune 500/international companies - it's not going to happen anytime soon.