If like me you are considering migrating from Apple’s MobileMe to a more open (and free) repository for your PIM data, then Google’s Gmail could be the answer.

Once you have setup your Gmail account simply export your contacts from Address Book or MobileMe, then import directly into Google.

In Mac OS Address Book go to Preferences > Accounts and tick the ‘Synchronise with Google’ option. Enter the Google Account and Password that you wish to synchronise with. You may find that your contacts don’t appear immediately, but you can force a resync via iSync. To do this open iSync, go to Preferences and tick on ‘Show status in menu bar’. To force a manual resync click on the iSync icon (swirly arrows) in the Mac OS menu bar and choose ‘Sync Now’.

The default automatic sync interval is set to 1 day. This can be changed by editing the StartInterval key in ~/Library/LaunchAgents/com.google.GoogleContactSyncAgent.plist which has a default setting of 3600 seconds (1 day). I changed this to 300 seconds, which forces an automatic re-sync with Google every five minutes.

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
<key>Label</key>
<string>com.google.GoogleContactSyncAgent</string>
<key>LimitLoadToSessionType</key>
<string>Aqua</string>
<key>ProgramArguments</key>
<array>
<string>/System/Library/PrivateFrameworks/GoogleContactSync.framework/Versions/A/Resources/gconsync</string>
<string>--sync</string>
<string>com.google.ContactSync</string>
<string>--periodic</string>
</array>
<key>StartInterval</key>
<integer>3600</integer>
</dict>
</plist>

Finally you should check through all your contacts to ensure that they comply with Google’s ActiveSync limitations:

The iPhone can synchronize up to 3 email address. Phone number synchronization is limited to 2 Home numbers, 1 Home Fax, 1 Mobile, 1 Pager, 3 Work (one will be labeled ‘Company Main’) and one Work Fax number.

Aside from some teething troubles when Google’s Calendar service went down last week, this setup has proven to be reliable and I can now keep my PIM data in sync between Mac, iPhone and Android devices.