Syncing the iPhone can be inconvenient. You have to plug in the phone etc etc etc to make sure your contacts and calendars are backed up. If you're like me you get caught with new contacts and calendars on your iPhone, forget to sync to the computer, and then lose them all on a restore (presumably after you ****** up with some sort of modding).
To date probably the simplest way around this problem is the mac solution of MobileMe which syncs your contacts and calendars over-the-air to your account and then to your computer. The problem? MobileMe costs some $$$.
Enter the Google. Something super simple, uses the iPhone's built in functionality (no extra app needed), and best of all Free.