You can get serial to wireless converters from B&B Electronics (http://www.bb-elec.com) which use either generic (WiFi and Bluetooth) or proprietary protocols and are designed to work in an industrial environment. These devices basically make it look like the serial port is attached to the host PC.
Prices typically range from around $250 to over $700 for mesh-style wireless and they have dev kits for around $170 if you are a DIY-type.
DigiKey also has wireless dev kits, if you are so inclined.
HTH,
Chris.