"Preparing to Get Root on your Phone
"Getting root on your phone involves exploiting a security hole that existed in an early version of Android. The versions with the security holes are known as RC19, RC28, and RC29 (or RC7 or lower for UK phones). As of RC30 (RC8 on UK), Google patched the security hole so that your phone can not be rooted (don’t worry, we can still root it!).
"To check your version, go to the Home Screen, click your menu button, choose "Settings", and then click "About phone". You will then see the following screen:
