QUORTZ  I have Rosetta installed, but I'm not sure how to determine if it's being used in this case? I don't think so though, because previous to Snow Leopard, I never had this Epson Printer Utility Lite... I had Epson Printer Utility2 and Epson Printer Utility3. Those two utilities remained on my drive after I updated to OS 10.6, but they wouldn't work at all. The new "Lite" utility worked fine, but not until this driver update 2.1 would it show the ink levels for the printer on the AirPort network. So yes, the "Lite" utility is working over AirPort. But in addition to head cleaning and adjustment, it now displays the ink levels, finally (I wasn't able to check the ink levels on the AirPort printer under Leopard either... it would just say, "Information is unavailable.").  
(Version 2.1)

QUORTZ  Before trying this install on my MacBook Pro (late '07 model, OS 10.6.1), I ran Software Update. SU indeed wanted to update the drivers for my Epson RX680 (and CX7800, which is a network printer on AirPort). Afterward, both printers perform just fine, and now the Epson Printer Utility Lite shows the ink levels for the AirPort printer... something I have never been able to do since putting that printer on a network. So, I'm a happy camper.  
(Version 2.1)

QUORTZ  10.5.7 caused no problems at all with my AirPort Express. In fact, it has caused no real problems with anything else either.  
(Version 5.4.2)

QUORTZ  Agreed.  
(Version 3.5.1)