Sorry to bump an old thread, but I'm bored at work
And since this topic is still in the top few threads, I didn't think anybody would mind.
What ISO setting were you using? If you go too high, the pictures will be too grainy. For what you're doing, 30 seconds may be too long too. Here's a couple of night pictures that I took so you can get an idea of settings to use.
This one was at ISO800 with 1/1000 exposure.http://www.flickr.com/photos/29290522@N ... hotostream
And this one was ISO800 with a 2 second exposure. http://www.flickr.com/photos/29290522@N ... hotostream
edit: one more thing I forgot to mention is to use the timer function on your camera. You shake the camera a bit when you push the button. Set the timer for 5 seconds and the camera should have stopped shaking from your press to take a steady shot.