Is it possible to disable the system update notification? I have a Nexus One that I want to keep at v2.2 for testing purpose. But the update 2.3.4 has been pushed to my phone and I keep seeing the notification to install it. Is it possible to disable the system update notification?
I believe the only way to stop the OTA notifications for good is to unlock/root the handset and install FOTAkill.apk to the /system/app/ directory.  The version of this app for Froyo can be found within the GApps package.

You might also need to "fake" your phone's signature by modifying the /system/build.prop file and altering the ro.build.... lines, so that they match the latest OS version.

On my Nexus One (it's rooted and running CyanogenMod 7) these are the relevant entries:

ro.build.id=GRI40
ro.build.display.id=GRJ22
ro.build.version.sdk=10
ro.build.version.codename=REL
ro.build.version.release=2.3.4
ro.product.model=Nexus One
ro.product.brand=google
ro.product.name=passion
ro.product.device=passion
ro.product.board=mahimahi
ro.product.manufacturer=HTC
ro.build.description=passion-user 2.3.3 GRI40 102588 release-keys
ro.build.fingerprint=google/passion/passion:2.3.3/GRI40/102588:user/release-keys


In either case you will need to root your N1.