I hadn't thought about it until I got my phone home, but the sensor works just fine with the 3GS. As expected, the app is identical to that on the touch, although Apple posted a tech note regarding answering calls while using the Nike app, something you don't worry about on the touch. If you've never tried using the Nike sensor with either a touch or the iPhone, read on. Oh, and I don't have a Nike remote watch doohickey, but apparently those will work on the 3GS as well. If the Nike thing isn't your bag, we ran down some competitors a while ago.
To pair the device, go to Settings > (in App-specific settings) Nike+iPod and flip the switch to ON. At the bottom (you can see in our gallery) choose either Sensor or Remote, depending on what you've got, and you'll be prompted to move around (sensor) or press a button (remote). That's all there is to it -- the proprietary wireless connection kicks in and pairs the two devices instamagically.
Just like previous iterations of the Nike system, you can change the PowerSong, voice, and units. One new twist: a new Lock Screen pref that will alter the locked-screen display to read in portrait or 2 available landscape modes. Very handy if you have a mount on your treadmill. What, you don't have a mount on your treadmill? Me either.
Now, after pairing, you should have a shiny new app on your screen that has the Nike logo and a plus sign. Unfortunately, my sleepy morning eyes couldn't find the app, but a Spotlight search found it for me. Here's Apple's notes on setting things up.
Keep reading for a short round-up of how the unit works while running.