Sure, set up one with a 433MHz Transmitter, the second with a 433 MHz Receiver, use the Virtual Wire library to send and receiver a message.
http://www.airspayce.com/mikem/arduino/VirtualWire/
Tx:
Rx:
A set of the units:
http://www.yourduino.com/sunshop/index.php?l=product_detail&p=341
Also has links to VirtualWire library
Don't forget to add 17cm of simple wire for an antenna