Bharat Suneja, a Senior Technical Writer at Microsoft just wrote the post below:
You Had Me At EHLO... : GAL Photos in Exchange 2010 and Outlook 2010http://msexchangeteam.com/archive/2010/03/10/454223.aspx
On this post you can see How to use the thmbnail preview that MS has been using in live demos of Exchange Server 2010 as well as the new Outlook Social Connector, http://blogs.msdn.com/outlook/archive/2009/11/18/announcing-the-outlook-social-connector.aspx.
As always, Microsoft is releasing what "You" have asked for :)
Kind regards and enjoy the post.