adb is a command-line utility that interfaces with Android phones.
Open up Terminal.app. Find the "adb" file and drag it into the Terminal.app window, it should produce something like:
"/Applications/android-sdk-mac_x86-1.5_r1/tools/adb"
After "adb", type a space, then "shell". You should now have a shell on your phone -- the prompt will change to simply "$" if you do.
Example:
Code:
howie @ macpro:[~]
10:28:11 (120) /Applications/java/android-sdk-mac_x86-1.5_r1/tools/adb shell
$