If you use Google's GMail for contact management or Google Calendar for events, you've probably felt the pain in keeping things synchronized between the online services and your mobile device. It was never impossible to do, but usually required more hassle than it should have. Mac-iPhone users often resorted to a combination of Apple's MobileMe service along with a 3rd party program like SpanningSync or BusySync, while Windows Mobile users would use something like OggSync.
Today Google rolled out Google Sync (beta) a service that should simplify synchronizing your Google Contacts & Calendar events with your mobile device. Just be careful and back up your information on your mobile device, the Google Sync will wipe the existing (local) information before the sync starts the first time. Additionally, due to different formats not all information may be synced. Be sure to check out the known limitations for the iPhone & Windows Mobile. let me say it one more time, back up your information before you start the sync.