Currently when using multiple calendars (Outlook.com, Google, iCloud and so on) all those are individual. One can see the hub view for those on Windows Phone of course but how about adding something to Google and seeing it on Outlook.com calendar also? So full bi-directional(multi-directional) sync is what I'm after for I suppose.
You can search for a app in Market or go to google calendar and see if there is a import option. Look: http://www.makeuseof.com/tag/how-to-sync-windows-live-and-google-calendar/
To view a calendar from Windows Live Calendar in Google Calendar, log into your Windows Live account and open the Windows Live Calendar website. Click the Share button at the top of the page and select the calendar you want to sync.
Enable the Send people a view-only link to your calendar check box on the sharing page. Click the ICS link under Links that show event details.
Select the link that appears and copy it to your clipboard (right-click the selected text and click copy.)
Next, log into your Google account and open Google Calendar. Click the arrow to the right of Other calendars and select Add by URL.
Paste the URL you copied earlier into the URL box. However, change the webcals:// at the beginning of the URL to http://. If you don’t make this change, Google Calendar will fail to understand the URL.
Once you’ve done this, click Add Calendar and the calendar will appear in your Google Calendar account.
Google Calendar will automatically check the calendar for updates. Any changes you make in Windows Live Calendar will appear on your Google Calendar. To add other calendars from Windows Live Calendar, repeat this process.
You can click the arrow to the right of the calendar in your calendar list to assign a color. Click the Calendar Settings link after clicking the arrow to assign a name to the calendar."