my nexus one shows as green, yes, i have all the latest software, but no fix yet for the touchscreen issue. That alone would make the nexus one RED since launch on that table for me, as this hints to zero support.
try to use your touch screen for 10min while the device is charging from an empty battery (some other use cases also trigger the bug, but this is 100% reproductible)
if this does not happen to your phone you are in the happy minority of nexus one users.
to the rest of us, while using the touch screen for extended periods of time (shorted if using both fingers and/or charging) it will start to behave erradicaly. Touching one area will register a touch somewhere else. This is also affected by the pressure. the harder you press the less likely to see the bug. It will get worse and affect larger areas until you turn the screen off and on again (lock, unlock and it's back to perfect condition)
worth to mention, this does not happens with some mods. but i haven't rooted my phone as i use it mostly for development and like to test against the stock image.
the car charger+gps app is in fact the worst case, as it will not need touch screen usage to happen. and will happen very fast and all the time. so basically, using the gps for more then 20min, i know i will have to: press power button to turn screen off, press it again to turn screen on, type PIN, press the damn gps button i needed to press 2min ago.