iOS users have long had the ability to control their cameras with their iPhones and iPads, but DSLR Controller now brings that to Android for your Canon DSLR.
The software is currently in beta, but getting it working took less than a minute. You just grab it from the Android Marketplace and connect your Canon DSLR via USB (you'll need a USB host cable if your Android device doesn't have a regular-sized USB port). Presuming the app is loaded and your camera is on, you should see what your camera sees in the main viewer on the screen. Because all this data is happening via USB, it updates really quickly and is far more usable than the Live View support you'll get over Wi-Fi on an iPhone app.
In addition to Live View, DSLR Controller lets you adjust pretty much every setting on your camera (e.g. aperture, exposure, ISO, etc), can take photos and more. While the app is currently in beta and might not work for every camera, it worked great with my 5D Mark II and support should broaden in the future. If you've ever tethered your camera to your computer or an iOS device before, you know the experience is not ideal. DSLR Controller, on the other hand, isn't cumbersome or slow. It's a very promising option for tethered shooting.
DSLR Controller ($8.31) [Android Market]