Recent Contacts View
There is a new view called "Recent Contacts" as per the following screen shot. There is also a view "My Contacts".
Basically the My Contacts view should contain just those people you have actually added yourself to your contacts. The Recent Contacts View will show everyone that you have corresponded with via email/calendar invites etc. The new feature basically automatically adds every person that you email to the Recent Contacts view so that they then appear in your type ahead when sending new emails/calendar invites etc.
I personally quite like this as it means I don't have to add everyone to "My Contacts" in order to then use type ahead for their email. This saves me time in that I don't have to find their email in order to send another email back to them.
However for those that don't like this feature you can stop people being automatically added to your Recent Contacts view thru a user preference. From the Contacts database go to the More-Preferences Action Item (as per following screen shot)
Then untick the following check box:
This will prevent contacts automatically being added to the Recent Contacts view.
Hope that helps.