Install BetterBatteryStat and monitor. That would be the best way of checking whatever that is waking up your phone unintentionally.
Found out that Samsung Push Service is usually the culprit. I've uninstall the samsung push service.
Try to disable auto-update feature as well.

Settings -> Applications -> Manage Applications
Look for it and uninstall.

I haven't found out what is not working after uninstalling the samsung push service.
My guess is that all samsung related app which has push services won't work anymore