One of the things that the Macbook Pro line of computers doesn't come with is a built in serial port. The solution to this is USB serial adapters, including the DSE USB Serial Adapter (DSE XH8290). Most of these use the FTDI USB/Serial chipset, which fortunately is reasonably well supported on both Linux and OS X, at least these days. (However the drivers on the DSE site are ancient and do not work with OS X 10.5 or 10.6; there are newer drivers on the FTDI website. v2.2.14 released 25 August 2009 is needed for Mac OS X 10.6.) Once the driver is installed, when the DSE USB Serial Adapter is plugged in it will be available as /dev/cu.usbserial-SERIAL where SERIAL is the electronic serial number of the USB device. kermit, from MacPorts, can be used to talk to the serial port.

FTR, with my DSE USB Serial adapter in my bag this is:

kermit
set line /dev/cu.usbserial-OCBAMD67
set carrier-watch off
set speed 9600
c

when talking with a non-modem device at 9600 8n1 (common for serial console on various devices).

Arduino

The Arduino Duemilanove board is has a USB Serial FTDI chip on it, so that the same driver will work with that board too.

The Arduino installation instructions for OS X cover installing the rest of the software needed for the Arduino Programming Environment, which is a Java-based IDE for programming. (It's also possible to do command line programming of the Arduino with the same toolset installed.) Note that despite the instructions the Arduino OS X software is installed like any other Arduino software -- drag it out of the DMG into the applications folder.

The Arduino serial port is similarly /dev/tty.usbserial-SERIAL where SERIAL is the electronic serial number of the Arduino device; mine is /dev/tty.usbserial-A7006RhM. In the Arduino software this can be chosen in Tools -> Serial Port, and the board should be set in Tools -> Board.