This is a driver for the many-and-various Prolific PL2303 serial-to-USB adapters that are out there.I just updated it to work on OS X Lion (10.7) and OS X Mountain Lion (10.8).
I forked this project from failberg/osx-pl2303.
A compiled kernelmodule and installation help can be found at: http://xbsd.nl/2011/07/pl2303-serial-usb-on-osx-lion.html.
I'm happy to receive pull request for updates or patches.
If you need to add additional device IDs or vendor IDs, those live in Info.plist; just clone the relevant section of the plist XML and create a new stanza - and be sure to send me a patch!
Thank you to B.J. Arnoldus for writing the driver in the first place, Michael Haller for patching the driver to work under SL, and the various folks who contributed patches to the Sourceforge tracker, some of which I've applied here.