JMyron relies on a native library, and the included one is not a universal binary. I grabbed their source and compiled it for intel- based macs (just i386 though - I didn't target universal. read: don't use on ppc macs). Have tested on 15" macbook pro and a mac pro. The file to replace is:

/Applications/Processing 0115/libraries/JMyron/library/libJMyron.jnilib