I also have a mac and initally had problems. I installed the FT drivers from the FTDI Chip manufactures website. If you go to the following link:http://www.ftdichip.com/Drivers/VCP.htm
And scroll down just a bit, you will see the driver download links for Mac OS. The current version is 2.2.17. They have both 32 and 64-bit versions installed.
BTW, I have since switched from using the Mac directly to using VMWare.Fusion and Win7x86. The reason for this is that the X-CTU application that is used to update the XBee modules is not avialble for the Mac and only works on 32-bit windows.I also had problems getting the OTA functions to work on the mac.
...but if you are just using the Waspmote IDE and sending the code to the board over USB, you should have no problems on the Mac once you install the FTD drivers. Just remember to remove the Zigbee module from the Waspmote board (as indicated in the checklist) before connecting the USB as they both share the same UART.