This is pretty cool. Google has set up a way to seamlessly bridge the gap from the iPhone Contacts and Calendars to Google’s online Contacts and Calendars.
For someone like me, who loves to use Google apps when I’m at my computer, but also constantly uses the iPhone for the same tasks when I’m away from the computer, this is a godsend. Now, when I get someone’s number or set an appointment from my phone, that info is available from my Google account when I go online. And the same holds true in the opposite direction. So, when I create a Calendar event from my computer, my phone will remind me.
A word of caution, though, setting it up the first time around can be tricky. The Google Contacts (Login to Gmail, click the Contacts link in the left navigation area) are kind of funny. You have a group called My Contacts, which is the only group that gets synchronized to the iPhone. So, be sure that any contact you want to be able to reach from your phone is in that group. Also, be aware that unless you’ve synched your iPhone calendar to Outlook or another desktop application, you WILL lose all iPhone-created calendar events when you set up Google Sync.
Of note: Google is using a Microsoft protocol to enable data synchronization with an Apple product.  Three huge players in the software biz, all direct competitors at some level, in perfect harmony here.