The OS X drivers will work, but without OS X drivers from Logitech, the functionality of the webcam maybe limited.
Even with Logitech drivers, I have found that the Mac version of the drivers are severly limit the webcam's functionality.
PC drivers for the same webcam appear to have more robust operating functionality.
I had purchase, fairly recently, 2 Logitech webcams that were the same model but could work on both Mac and PC.
I was using the webcam on a G4 MDD tower and my girlfriend used the other webcam on her PC.
With Logitech drivers installed, I had less functionality of the webcam than my girlfriend had with the same webcam using the Windows PC drivers on her PC.
Example, the auto focus function worked well on the PC, but this function did not work on my Mac.
Auto focusing based on moving subject worked great on her PC, but no such function existed for the Mac OS X version.
FYI