Depends on the kind of work you do. If you're in sales or marketing the open office plan may indeed stimulate creativity or whatever.

But for people who have to concentrate (like software developers) it's a productivity killer. Joel Spolsky used to touch on this occasionally - he claims all sorts of research shows the most productive arrangement is to put everyone in his own office with a door.

Where I work that will never happen, because there are corporate-wide rules about who gets an office and who doesn't. You have to be a director to get your own office, which is two levels above non-managers. They're so anal about it one time I worked on a floor with no directors and they left all the offices unoccupied. They crowded everyone into cubes and even doubled one up when they ran out of (cubicle) space.

Then the question comes: Do they really save money, or does it just appear like they do?

Saving money on office space is money saved. People being distracted and doing poor work is money lost. I wonder how it sums up.

Money saved on office space is easily measurable and directly attributable to the bean counter responsible.

Productivity loss is hard to measure, and even when it's blatantly obvious, it's easy to shift the blame.

It highly depends on the team. In a small team that know each other well, it can work. Most of the time it's not the case, however.