This is mostly just a note to myself, but I figured some other people might find it useful. When I connected my Nexus One, it was showing up as “???????????? no permissions” when I ran adb devices. I added the typical udev rule and had no luck. Running lsusb revealed the the vendor ID is different from the HTC G1. So, to enable debugging this device and the G1 in Ubuntu (and other flavors of Linux), create/edit /etc/udev/rules.d/51-android.rules and put the following in it:

SUBSYSTEM=="usb", SYSFS{idVendor}=="0bb4", MODE="0666"<br /> SUBSYSTEM=="usb", SYSFS{idVendor}=="18d1", MODE="0666"

You may need to run sudo reload udev and/or disconnect and reconnect the N1. Check adb devices again and hopefully you’ll see “HT9CSP123456 device” or similar.