We have a variety of devices for testing purposes, and now that Froyo is being pushed (to the Nexus One so far at least), we have to constantly dismiss upgrade requests. There is no apparent "stop asking me" button.
So, is there any way I can disable OTA OS updates? We want a number of these phones to stay on old OS versions.
Remove SystemUpdater.apk from /system/app. From terminal (with ADB)
adb pull /system/app/SystemUpdater.apk C:/Path/to/your/desktop //Backup the file (just in case)
adb remount //Remount the system partition to read-write
adb shell rm /system/app/SystemUpdater.apk //Remove the apk
Warning - this will permanently disable system updates, until you push SystemUpdater back to /system/app