After releasing one-click-root methods for the Motorola Droid X and the Samsung Galaxy S, the XDA developers community has now released a new app which allows you to root your Nexus One with just one click. The method used is the same as the one used to root the Droid X.
It also doesn’t unlock the bootloader, keeping your warranty intact. You can download it from here: 1-Click-Root for Nexus One – XDA
The best thing about the UniversalAndRoot app is that it works with many Android phones. Here is a list of the phones it supports
Google Nexus One (2.2)
HTC Hero (2.1)
HTC Magic (1.5)
Dell Streak (2.1)
Motorola Milestone (2.1)
Motorola XT800 (2.1)
Sony Ericsson X10 (1.6)
Sony Ericsson X10 Mini Pro (1.6)
Acer Liquid (2.1)
Vibo A688 (1.6)
It doesn’t work with the Galaxy S, Droid X or the HTC Desire, but the devs are working on it.