I searched for similar questions on this issue but found none related to Mac OSX.
Situation: Trying to test android apps on a Galaxy S (D
Have you tried connecting the phone using a powered USB hub? I haven't tried it yet but found this blog post that suggests it may help for Samsung Galaxy devices.
http://esausilva.com/2010/10/02/how-to-set-up-adb-android-debug-bridge-in-mac-osx/