Hi, The Garmin Communicator plugin 4.0.1.1 resolved an issue I was having trying to copy files to my GPS. I can confirm it works with:
imac 2.5Ghz, OS 10.7.3, Safari 5.1.4
if you have version 4.0.1, and you have trouble getting the file to save to the GPS, install 4.0.1.1 -it fixes the issue. There is another discussion about this very problem in another thread.
Moun10Bike provided the solution.
Hope this helps
thanks