Did you get an alert in the status bar? You should be able to pull down the status bar menu and select the option to enable usb. If not, then you may need to install the drivers, which can be downloaded from samsung.
I figured it out, I had to install the drivers through the Android SDK. You install some kind of file manager and choose to install only the Google USB drivers. It was somewhat of a timely process. I wish you could just install the dang thing from google.com somewhere.
Alternatively, you can install it with PDAnet, which was a lot easier (did that on my work computer), but it doesnt seem to be working for everyone.