Its not necessarily which camera to use to take night shots, but what additional accessories you have to go with it. Most digital P&S cameras will let you change your own settings. In other words, get off the program modes (all those little icon's on the dial) and set it to M or S or A (I believe canon's are M, Tv and Av). This allows you to set your own Shutter speed and/or Aperture.
The most important accessory is a tripod. I would also recommend a remote shutter release if the camera works with one (not all do), or at least use the self timer to help avoid the camera shaking when you press the button to take a picture.
You can pick up tripods on line for very inexpensive money. There are what they call 'travel' tripods. Ones that close up to about 13-15 inches, but when opened will be about 42-48 inches high. 13-15 inches will fit in a normal sized backpack. There are also tiny pocket type tripods which are also called 'table top'. They are only about 6 inches or so and can be set up on a trash can, table, ground, anything solid. They go for about $10-15.
I picked up a 43 1/2 inch tripod that closes down to 13 1/2 inches off amazon.com for about $20. It fits in my backpack and is very light weight. I'll use it at Disney for night shots and will probably also keep it in my car.
You can also spend a little under a thousand dollars and get a dSLR (NIKON, canon, pentax, minolta) with a prime lens that will open up to f/1.8 or 1.4. (Nikon D50 body, $599 and Nikkor 50mm f/1.8 lens $120) Crank up the ISO to 1600, lean against a post, hold your breath and snap the picture. But I'd go with the tripod.