Here is a good news for N1 users, one-click root application is now released for the Nexus One smartphone. According to the developer, it uses the same exploit that was used to root Droid X. The app DOES NOT unlock the phones boot-loader, which means it doesn’t void your phone warranty.
This rooting application listed at XDA-Developers also allows installation of custom ROMs and currently supports 12 Android devices. There seems support for 1-click unroot as well. You need to be a member of XDA-Developers to download the rooting app, but for your convenience, I’ve uploaded the file which you can directly download below:
UniversalAndroot.apk [Direct Download Link]