Can the modules [Parallax 32440-RT XBee Wireless Pack](http://Parallax 32440-RT XBee Wireless Pack) Be Connected * just the module not the adapter boards* into the Wireless shield http://arduino.cc/en/Main/ArduinoWirelessShield, And is the second unit required or will it communicate directly your wireless network ?
Yes.
The XBee in that pack cannot be used in a WiFi network though. You need a second one.
so the second one in that pack would have to be used 
VIA serial?