Most definately! Video proof of wrondoing is the kind of evidence that someone can't really talk thier way out of.
As a business owner I know how hard it is to take time off from work without worrying. I've used my surveillance system to "check in", several times, when I was home taking care of my daughter because she was ill. It was nice to be able to see that everything was going smoothly even without me.
Some systems can be set to alert you when they detect motion as well. If you get an alert to your cell or PDA after hours you can easily log in to find out what's happening.
A friend of mine, who is in the construction industry, just saved quite a bit of money when he found that an employee was returning after work to steal matrials from his company. He had installed the cameras thinking he was going to catch the "thieves" who kept robbing his job sites. If he had cameras on his job sites before this started he could have saved a lot more.