Google has released a beta of Google Sync that enable you to sync your Google Calendar and Gmail Contacts to those in your iphone. This free service by Google also supports similar sync for Windows Mobile devices.
This is handy for people who rely on Google tools and require the calendar and contacts info on their iphone. Please note that Google Sync will replace all your existing contacts and calendar on your iphone, be sure to backup important data before you try out the service.
For those who uses Apple’s Calendar and Contacts on their Mac and iPhone, Apple’s $99 per year MobileMe service is the option that would enable you to access your calendar and contacts over the internet.
The setup for Google Sync is slightly more complex, it uses the Microsoft Exchange ActiveSync technology on the iphone thus requires the setting up of a new Exchange ActiveSync account on your iPhone. Google provides step by step setup guide to enable Google Sync on your iphone.