Who Knows the Admin. Passwords in your IT Dept.?

I work for a small company in which we have 5 IT staff members supporting about 100 users. I’m curious what the norm is out there for securing the administrator passwords? Does everyone in your IT department have access to the administrator passwords, or are they restricted to certain individuals? Assuming they are restricted to certain individuals, how do you give administrative privledges to those individuals who don’t know the passwords and need to do something that requires elevated priveledges?