It looks like the problem with Mac::Carbon on Intel Macs is that we are passing a string (for example, 'MACS', the four-char code for the Finder) and then converting it into an integer, which on Intel, gets the endianness wrong.
Matt Sachs helped me with some iChat-based debugging, and Matthias Neeracher gave me a fix, which is in the process of being tested and stuff.
