My newer notebook, a Dell Latitude D600 (from the "corporate/business" Latitude lineup) has no PS/2 ports. It's commonplace nowadays in notebooks to eliminate the PS/2 ports in order to save space, weight, and cost. This change has been made possible because USB mice and keyboards are now commonplace and highly compatible.
OP: Yes, you can use a wireless mouse as long as it uses USB, and you have both portions: The receiver, which plugs into the USB port, and the mouse itself. Once the receiver is plugged into the port, the computer doesn't know the difference between the USB receiver/wireless mouse combo and a regular wired USB mouse, so either type of USB mouse works fine on any computer with a USB port.