This is a common term used to mean radio transmission. Although there are no wires in Infra Red, it is not what people generally mean when they say wireless.

Good examples are RC cars, Bluetooth - a Wireless device communication stack, WiFi and CyberMaster - A Wireless Lego Robotics platform.

Building a robot with wireless communications system may mean they are able to communicate and download new programs fairly easy.
In fact, early robots - like Shakey, were connected to huge computers via a radio link.

These are however susceptable to interference- and without encoding - interception or corruption. While these would present great troubles to a home grown or raw protocol, Bluetooth and WiFi deal with such problems fairly well.

Beware - noisy motors without supressor caps may seriously degrade signal quality (and therefore range and download speed) quite significantly. If you are intending to sell any robot - you must consider the various RF laws and recommendations. Many bandwidths are pre-allocated, so using the hobbyist 27mhz band is recommended.