Having the same problem. This solution did not work on 2 different Macs. At this point we must consider that Mac Mavericks will be unusable on Arduino. The Arduino home page should list there products as no long compatible with Macintosh until this is fixed. Such a shame. I was really getting into using Arduino products but will have to quit until this is resolved.
this worked for me thank you, having a hell of a time getting arduino and processing to work together problem seems to be in the line that assigns the connection to be my arduino usb connection. Using old tutorials from o'rielly, bought the arduino/processing tutorials but can't get the arduino and processing sketches to talk to each other. Dropped the baud rate to match the arduino, 9600, loaded the firmata to my board(using a duemilinova board.... Really want to introduce students to processing and then connect to the arduino environment but the frustration I have been experiencing makes it difficult to put together a lesson plan and workflow criteria-too many problems and don't want to be dealing with them in class any suggestions?