David Green at MacInTouch reports:

“The new AirPort Extreme v5.5 and AirPort Express v6.1 firmware upgrades break wireless printing for some printers, most notably the Brother HL-1440 (which Apple sells) and HL-1240 (which is technically unsupported by the AirPort, but has worked anyway).

“Users with an AirPort Extreme can downgrade back to v5.4 via a firmware installer on Apple’s support area, but users with the Express are out of luck… there is no installer for v6.0. One user reported swapping with an AirPort Express at his local Circuit City. Others are recommending returning recently bought Airport Express units for non-upgraded shelf stock at the Apple Store, or wherever.

“A large and growing thread can be viewed on Apple’s discussion page at: Apple - Discussions - WARNING ON NEW AIRPORT SOFTWARE-PRINTING.”