I have the CP-US-03 by CP Tech USB to Serial adaptor and have used that I have used for years. The manufactures driver always worked will for Windows and with kernels 2.6.11 and later, it is plug and play in Linux. With the new MacBook Pro, the provided CP Tech drivers did not work.

I went through the steps to install the driver and after the required reboot, there was no devices listed in the /dev/ directory. I did found that the CP Tech device was based off the Prolific PL2303 chipset. Ultimately, this website included a version of the driver that worked for Mountain Lion.  After a reboot, my Cisco console access was back.  The output of ls /dev/tty.* is below.

Device Listing including the PL2303 as "tty.usbserial"