Currently Being ModeratedApr 27, 2013 8:23 PM (in response to WakadooJon)
It is a network printer, and Xerox has OS X Lion drivers for it, so it should work but not "wirelessly" in the strictest sense - it requires an Ethernet connection to your Express's LAN port, but wireless Macs will be able to use it as much as everything else on your LAN.
Follow the instructions here: OS X Mountain Lion: Set up an IP printer
The instructions are identical for Lion.
It is best to assign printers a static IP address.MacBooks iMacs iPads AirPorts, OS X Mountain Lion, 28 years Apple!