Omnia2 (GT-I8000) running Windows Mobile 6.5 has a vibration feedback for taps on the screen. It happened to me suddenly, that the vibration was gone, even when I enabled it in the Settings, Sound Settings, Touch Alert, Alert (set to "Vibration" or "Sound + Vibration").
Searching the Internet for this turned up more noise than signal. So, digging into the registry, I found this key HKEY_CURRENT_USER\ControlPanel\VibeTonz.
It turned out that the strength of the vibration could be configured, and it was set to 0.
TouchVibeStrength (DWORD:0-5) controls the strength of the vibration.
TouchSoundOn enables sound feedback.
TouchVibeOn enabed vibration feedback.