Regarding the possibility of connecting an HP 49G+ to a Mac

I did a little research, and realized that there's already a program that (theoretically) will talk to my new calculator -- the ancient, venerable ZTerm. The HP 49G+ (and indeed, the other HP graphing calculators) can send and receive files via XModem or Kermit. Unfortunately, when I plug the calculator in using its built-in USB port, it is not recognized as a serial device by either Mac OS X or Windows XP. Hewlett-Packard wrote a device driver and a separate XModem client to achieve connectivity under Windows, and that's probably what I'll have to do under OS X.

I also saw this little blurb on the aforementioned IOKit homepage:

The I/O Kit also provides a parallel user space API using a plug-in mechanism, called device interfaces, which allows developers to perform driver-like functions from application code. This in many cases avoids the need to write kernel drivers.

Yay! Hopefully I won't have to fuck with Mac OS X's Darwin kernel!